Internet - Introduction to Internet, Important Definition, Components of Internet
Introduction to Internet
Introduction
What is the Internet?
History & Development of Internet
What was ARPANET?
Architecture of Internet
Important Definition
Important Definitions of Internet
Components of Internet
WEB Browsers
WWW
Web Pages
Website
HTML
HTTP
URL
Gopher
Introduction to Internet
Introduction
By the turn of the century, information, including access to the Internet, will be the basis for personal, economic, and political advancement. The popular name for the Internet is the information superhighway
Whether you want to find the latest financial news, browse through library catalogs, exchange information with colleagues, or join in a lively political debate, the Internet is the tool that will take you beyond telephones, faxes, and isolated computers to a burgeoning networked information frontier.
The Internet is a computer network made up of thousands of networks worldwide. No one knows exactly how many computers are connected to the Internet. It is certain, however, that these number in the millions and are growing.
No one is in charge of the Internet. There are organizations which develop technical aspects of this network and set standards for creating applications on it, but no governing body is in control. The Internet backbone, through which Internet traffic flows, is owned by private companies.
All computers on the Internet communicate with one another using the Transmission Control Protocol/Internet Protocol suite, abbreviated to TCP/IP. Computers on the Internet use a client/server architecture.
This means that the remote server machine provides files and services to the user's local client machine. Software can be installed on a client computer to take advantage of the latest access technology.
An Internet user has access to a wide variety of services: electronic mail, file transfer, vast information resources, interest group membership, interactive collaboration, multimedia displays, real-time broadcasting, breaking news, shopping opportunities, and much more.
The Internet consists primarily of a variety of access protocols. Many of these protocols feature programs that allow users to search for and retrieve material made available by the protocol.
What is the Internet?
The Internet links are computer networks all over the world so that users can share resources and communicate with each other. Some computers, have direct access to all the facilities on the Internet such as the universities. And other computers, eg privately-owned ones, have indirect links through a commercial service provider, who offers some or all of the Internet facilities.
In order to be connected to Internet, you must go through service suppliers. Many options are offered with monthly rates. Depending on the option chosen, access time may vary.
The Internet is what we call a metanetwork, that is, a network of networks that spans the globe. It's impossible to give an exact count of the number of networks or users that comprise the Internet, but it is easily in the thousands and millions respectively.
The Internet employs a set of standardized protocols which allow for the sharing of resources among different kinds of computers that communicate with each other on the network.
These standards, sometimes referred to as the Internet Protocol Suite, are the rules that developers adhere to when creating new functions for the Internet.
The Internet is also what we call a distributed system; there is no central archives. Technically, no one runs the Internet. Rather, the Internet is made up of thousands of smaller networks.
The Internet thrives and develops as its many users find new ways to create, display and retrieve the information that constitutes the Internet.
Internet
• A network of networks
Based on TCP/IP (Transmission Control Protocol/Internet Protocol)
Global
A variety of services and tools
A network of networks, or "internet," is a group of two or more networks that are: Interconnected physically capable of communicating and sharing data with each other able to act together as a single network
Machines on one network can communicate with machines on other networks, and send data, files, and other information back and forth.
For this to work, the networks and machines that are part of an internet have to agree either to speak the same "language" when they are communicating or to use an "interpreter."
This "language" is software that enables the different types of machines on separate networks to communicate and exchange information.
To be used by different types of machines yet be understood by all of them, the software must follow a set of rules, or protocol.
The Internet, with a capital "I", is the network of networks which either use the TCP/IP protocol or can interact with TCP/IP networks via gateways (the interpreters).
The Internet presents these networks as one, seamless network for its users
The Internet covers the globe and includes large, international networks as well as many smaller, local-area networks (LANs).
The Internet offer access to data, graphics, sound, software, text, and people through a variety of services and tools for communication and data exchange:
Remote login (telnet)
file transfer (ftp)
electronic mail (e-mail)
news (USENET or network news)
hypertext (WWW)
History & Development of Internet
In its infancy, the Internet was originally conceived by the Department of Defense as a way to protect government communications systems in the event of a military strike
The original network, dubbed ARPANet (for the Advanced Research Projects Agency that developed it) evolved into a communications channel among contractors, military personnel, and university researchers who were contributing to ARPA projects.
The network employed a set of standard protocols to create an effective way for these people to communicate and share data with each other.
ARPAnet's popularity continued to spread among researchers, and in the 1980's the National Science Foundation, whose NSFNet, linked several high speed computers, took charge of the what had come to be known as the Internet.
By the late 1980's, thousands of cooperating networks were participating in the Internet. In 1991, the U.S. High Performance Computing Act established the NREN (National Research & Education Network).
NREN's goal was to develop and maintain high-speed networks for research and education, and to investigate commercial uses for the Internet. The rest, as they say, is history in the making.
The Internet has been improved through the developments of such services as Gopher and the World Wide Web.
Even though the Internet is predominantly thought of as a research oriented network, it continues to grow as an informational, creative, and commercial resource every day and all over the world.
Modern computer networking technologies emerged in the early 1970s. In 1969, The U.S. Defense Advanced Research Projects Agency (variously called ARPA and DARPA), an agency within the Department of Defense, commissioned a wide-area computer network called the ARPANET.
This network made use of the new packet switching concepts for interconnecting computers and initially linked computers at universities and other research institutions in the United States and in selected NATO countries.
At that time, the ARPANET was essentially the only realistic wide-area computer network in existence, with a base of several dozen organizations, perhaps twice that number of computers and numerous researchers at those sites.
The program was led at DARPA by Larry Roberts. The packet switches were built by Bolt Beranek and Newman (BBN), a DARPA contractor.
Others directly involved in the ARPANET activity included the authors, Len Kleinrock, Frank Heart, Howard Frank, Steve Crocker, Jon Postel and many many others in the ARPA research community.
Back then, the methods of internetworking (that is interconnecting computer networks) were primitive or non-existent.
Two organizations could interwork technically by agreeing to use common equipment, but not every organization was interested in this approach. Absent that, there was jury-rigging, special case development and not much else.
Each of these networks stood on its own with essentially no interaction between them – a far cry from today’s Internet.
In the early 1970s, ARPA began to explore two alternative applications of packet switching technology based on the use of synchronous satellites (SATNET) and ground-based packet radio (PRNET).
The decision by Kahn to link these two networks and the ARPANET as separate and independent networks resulted in the creation of the Internet program and the subsequent collaboration with Cerf.
These two systems differed in significant ways from the ARPANET so as to take advantage of the broadcast and wireless aspects of radio communications.
The strategy that had been adopted for SATNET originally was to embed the SATNET software into an ARPANET packet switch, and interwork the two networks through memory-to-memory transfers within the packet switch.
This approach, in place at the time, was to make SATNET an “embedded” network within the ARPANET; users of the network would not even need to know of its existence.
The technical team at Bolt Beranek and Newman (BBN), having built the ARPANET switches and now building the SATNET software, could easily produce the necessary patches to glue the programs together in the same machine.
Indeed, this is what they were under contract with DARPA to provide. By embedding each new network into the ARPANET, a seamless internetworked capability was possible, but with no realistic possibility of unleashing the entrepreneurial networking spirit that has manifest itself in modern day Internet developments. A new approach was in order.
The Packet Radio (PRNET) program had not yet gotten underway so there was ample opportunity to change the approach there. In addition, up until then, the SATNET program was only an equipment development activity.
No commitments had been obtained for the use of actual satellites or ground stations to access them. Indeed, since there was no domestic satellite industry in the U.S.
then, the only two viable alternatives were the use of Intelsat or U.S. military satellites. The time for a change in strategy, if it was to be made, was then.
What was ARPANET?
ARPANET stands for Advanced Research Projects Agency (ARPA) Network. The network was developed in 1969 by ARPA and funded by the Department of Defense.
The network was chiefly experimental, and was used to research, develop and test networking technologies.
The original network connected four host computers at four separate universities throughout the United States, enabling users to share resources and information
By 1972, there were 37 host computers connected to ARPANET. Also in this year, ARPA's name was changed to DARPA (Defense Advanced Research Projects Agency).
In 1973, ARPANET went beyond the boundaries of the United States by making its first international connections to England and Norway.
One goal of ARPANET was to devise a network that would still be operational if part of the network failed. The research in this area resulted in a set of networking rules, or protocols, called TCP/IP (Transmission Control Protocol/Internet Protocol).
TCP/IP is a set of protocols that govern how data is transmitted across networks. It also enables different types of computer operating systems, such as DOS and UNIX, to share data across a network.
ARPANET functioned as a "backbone" network - allowing smaller local networks to connect to the backbone.
Once these smaller networks were connected to the backbone, they were in effect connected to each other.
In 1983, DARPA decided that TCP/IP would be the standard set of protocols used by computers connecting to ARPANET. This meant that any smaller networks (for example, a university network) that wanted to connect to ARPANET also had to be using TCP/IP.
TCP/IP was available for free and was increasingly used by networks. The spread of TCP/IP helped create the Internet as we know it today - the network of networks that either use the TCP/IP protocols, or can interact with TCP/IP networks.
Architecture of Internet
The authors created an architecture for interconnecting independent networks that could then be federated into a seamless whole without changing any of the underlying networks. This was the genesis of the Internet as we know it today.
In order to work properly, the architecture required a global addressing mechanism (or Internet address) to enable computers on any network to reference and communicate with computers on any other network in the federation.
Internet addresses fill essentially the same role as telephone numbers do in telephone networks.
The design of the Internet assumed first that the individual networks could not be changed to accommodate new architectural requirements; but this was largely a pragmatic assumption to facilitate progress.
The networks also had varying degrees of reliability and speed. Host computers would have to be able to put disordered packets back into the correct order and discard duplicate packets that had been generated along the way.
This was a major change from the virtual circuit-like service provided by ARPANET and by then contemporary commercial data networking services such as Tymnet and Telenet.
In these networks, the underlying network took responsibility for keeping all information in order and for re-sending any data that might have been lost.
The Internet design made the computers responsible for tending to these network problems.
A key architectural construct was the introduction of gateways (now called routers) between the networks to handle the disparities such as different data rates, packet sizes, error conditions, and interface specifications.
The gateways would also check the destination Internet addresses of each packet to determine the gateway to which it should be forwarded.
These functions would be combined with certain end-end functions to produce the reliable communication from source to destination.
A draft paper by the authors describing this approach was given at a meeting of the International Network Working Group in 1973 in Sussex, England and the final paper was subsequently published by the Institute for Electrical and Electronics Engineers, the leading professional society for the electrical engineering profession, in its Transactions on Communications in May, 1974 . The paper described the TCP/IP protocol.
DARPA contracted with Cerf's group at Stanford to carry out the initial detailed design of the TCP software and, shortly thereafter, with BBN and University College London to build independent implementations of the TCP protocol (as it was then called – it was later split into TCP and IP) for different machines.
BBN also had a contract to build a prototype version of the gateway. These three sites collaborated in the development and testing of the initial protocols on different machines.
Cerf, then a professor at Stanford, provided the day-to-day leadership in the initial TCP software design and testing. BBN deployed the gateways between the ARPANET and the PRNET and also with SATNET.
During this period, under Kahn's overall leadership at DARPA, the initial feasibility of the Internet Architecture was demonstrated.
The TCP/IP protocol suite was developed and refined over a period of four more years and, in 1980, it was adopted as a standard by the U.S. Department of Defense. On January 1, 1983 the ARPANET converted to TCP/IP as its standard host protocol.
Gateways (or routers) were used to pass packets to and from host computers on “local area networks.” Refinement and extension of these protocols and many others associated with them continues to this day by way of the Internet Engineering Task Force
Important Definition
Important Definitions of Internet
Back/Forward
Buttons in most browsers' Tool Button Bar, upper left. BACK returns you to the document previously viewed. FORWARD goes to the next document, after you go BACK.If it seems like the BACK button does not work, check if you are in a new browser window; some Web pages are programmed to open a new window when you click on some links.
Each window has its own short-term search HISTORY. If this does not work, right click on the BACK button to select the page you want (some Web pages are programmed to disable BACK).
BLOG or WEB LOG
A blog (short for "web log") is a type of web page that serves as a publicly accessible personal journal (or log) for an individual. Typically updated daily, blogs often reflect the personality of the author.
Blog software usually has an archive of old blog postings. Many blogs can be searched for terms in the archive.
Blogs have become a vibrant, fast-growing medium for communication in professional, poltical, news, trendy, and other specialized web communities. Many blogs provide RSS feeds, to which one can subscribe and receive alerts to new postings in selected blogs.
BOOKMARK/FAVORITES
Way in browsers to store in your computer direct links to sites you wish to return to. Netscape, Mozilla, and Firefox use the term Bookmarks. The equivalent in Internet Explorer (IE) is called a "Favorite."
To create a bookmark, click on BOOKMARKS or FAVORITES, then ADD. Or left-click on and drag the little bookmark icon to the place you want a new bookmark filed. To visit a bookmarked site, click on BOOKMARKS and select the site from the list.
You can download a bookmark file to diskette and install it on another computer. In most browsers now, you can do this with an Import... and Export... set of commands which can be found under FILE or in the Manage Bookmarks window's FILE.
BOOLEAN LOGIC
Way to combine terms using "operators" such as "AND," "OR," "AND NOT" and sometimes "NEAR." AND requires all terms appear in a record. OR retrieves records with either term. AND NOT excludes terms.
Parentheses may be used to sequence operations and group words. Always enclose terms joined by OR with parentheses. Which search engines have this?
See -REJECT TERM and FUZZY AND. Want a more extensive explanation of Boolean logic, with illustrations?
BROWSE
To follow links in a page, to shop around in a page, exploring what's there, a bit like window shopping. The opposite of browsing a page is searching it.
When you search a page, you find a search box, enter terms, and find all occurrences of the terms throughout the site. When you browse, you have to guess which words on the page pertain to your interests.
Searching is usually more efficient, but sometimes you find things by browsing that you might not find because you might not think of the "right" term to search by.
BROWSERS
Browsers are software programs that enable you to view WWW documents. They "translate" HTML-encoded files into the text, images, sounds, and other features you see.
Microsoft Internet Explorer (called simply IE), Mozilla, Firefox, Safari, and Opera are examples of "graphical" browsers that enable you to view text and images and many other WWW features.
They are software that must be installed on your computer. For more information about browsers, consult the introductory pages of the Teaching Library tutorial.
CACHE
In browsers, "cache" is used to identify a space where web pages you have visited are stored in your computer. A copy of documents you retrieve is stored in cache.
When you use GO, BACK, or any other means to revisit a document, the browser first checks to see if it is in cache and will retrieve it from there because it is much faster than retrieving it from the server.
CACHED LINK
In search results from Google, Yahoo! Search, and some other search engines, there is usually a Cached link which allows you to view the version of a page that the search engine has stored in its database.
The live page on the web might differ from this cached copy, because the cached copy dates from whenever the search engine's spider last visited the page and detected modified content.
Use the cached link to see when a page was last crawled and, in Google, where your terms are and why you got a page when all of your search terms are not in it.
CASE SENSITIVE
Capital letters (upper case) retrieve only upper case. Most search tools are not case sensitive or only respond to initial capitals, as in proper names. It is always safe to key all lower case (no capitals), because lower case will always retrieve upper case. Which search engines have this?
CGI
"Common Gateway Interface," the most common way Web programs interact dynamically with users.
. Many search boxes and other applications that result in a page with content tailored to the user's search terms rely on CGI to process the data once it's submitted, to pass it to a background program in JAVA, JAVASCRIPT, or another programming language, and then to integrate the response into a display using HTML.
COOKIE
A message from a WEB SERVER computer, sent to and stored by your browser on your computer. When your computer consults the originating server computer, the cookie is sent back to the server, allowing it to respond to you according to the cookie's contents.
The main use for cookies is to provide customized Web pages according to a profile of your interests. When you log onto a "customize" type of invitation on a Web page and fill in your name and other information, this may result in a cookie on your computer which that Web page will access to appear to "know" you and provide what you want.
If you fill out these forms, you may also receive e-mail and other solicitation independent of cookies.
DOMAIN, TOP LEVEL DOMAIN (TLD)
Hierarchical scheme for indicating logical and sometimes geographical venue of a web-page from the network. In the US, common domains are .edu (education), .gov (government agency), .net (network related), .com (commercial), .org (nonprofit and research organizations).
Outside the US, domains indicate country: ca (Canada), uk (United Kingdom), au (Australia), jp (Japan), fr (France), etc. Neither of these lists is exhaustive. See also DNS entry.
DOMAIN NAME, DOMAIN NAME SERVER (DNS)ENTRY
Any of these terms refers to the initial part of a URL, down to the first /, where the domain and name of the host or SERVER computer are listed (most often in reversed order, name first, then domain).
The domain name gives you who "published" a page, made it public by putting it on the Web.
A domain name is translated in huge tables standardized across the Internet into a numeric IP address unique the host computer sought. These tables are maintained on computers called "Domain Name Servers.";
Whenever you ask the browser to find a URL, the browser must consult the table on the domain name server that particular computer is networked to consult.
"Domain Name Server entry" frequently appears a browser error message when you try to enter a URL. If this lookup fails for any reason, the "lacks DNS entry" error occurs.
The most common remedy is simply to try the URL again, when the domain name server is less busy, and it will find the entry (the corresponding numeric IP address). For more information, see "All About Domain Names."
Download
To copy something from a primary source to a more peripheral one, as in saving something found on the Web (currently located on its server) to diskette or to a file on your local hard drive. More information.
EXTENSION or FILE EXTENSION
In Windows, DOS and some other operating systems, one or several letters at the end of a filename. Filename extensions usually follow a period (dot) and indicate the type of file.
For example, this.txt denotes a plain text file, that.htm or that.html denotes an HTML file. Some common image extensions are picture.jpg or picture.jpeg or picture.bmp or picture.gif
FAVORITES
In the Internet Explorer browser, a means to get back to a URL you like, similar to Bookmarks.
FEED READER
A software package that enables you to easily read the XML code in which RSS feeds are written. Bloglines is currently the most popular feed reader but there are many competitors.
FIND
Tool in most browsers to search for word(s) keyed in document in screen only. Useful to locate a term in a long document. Can be invoked by the keyboard command, Ctrl+F.
FRESHNESS
How up-to-date a search engine database is, based primarily on how often its spiders recirculate around the Web and update their copies of the web pages they hold, and discover new ones.
Also determined by how quickly they integrate new sites that web authors send to them. Two weeks is about as good as most search engines do, but some update certain selected web sites more frequently, even daily.
FRAMES
A format for web documents that divides the screen into segments, each with a scroll bar as if it were as "window" within the window.
Usually, selecting a category of documents in one frame shows the contents of the category in another frame. To go BACK in a frame, position the cursor in the frame an press the right mouse button, and select "Back in frame" (or Forward).
You can adjust frame dimensions by positioning the cursor over the border between frames and dragging the border up/down or right/left holding the mouse button down over the border
FTP
File Transfer Protocol. Ability to transfer rapidly entire files from one computer to another, intact for viewing or other purposes.
FUZZY AND
In ranking of results, documents with all terms (Boolean AND) are ranked first, followed by documents containing any terms (Boolean OR) are retrieved. The farther down, the fewer the terms, although at least one should always be present.
HEAD or HEADER
The top portion of the HTML source code behind Web pages, beginning with <HEAD> and ending with . It contains the Title, Description, Keywords fields and others that web page authors may use to describe the page.
The title appears in the title bar of most browsers, but the other fields cannot be seen as part of the body of the page. To view the <HEAD> portion of web pages in your browser, click VIEW, Page Source. In Internet Explorer, click VIEW, Source. Some search engines will retrieve based on text in these fields.
HISTORY, Search History
Available by using the combined keystrokes CTRL + H, a more permanent record of sites you have visited/retrieved than GO. You can set how many days your browser retains history in Edit | Preferences, or in Tools | Options.
HOST
Computer that provides web-documents to clients or users. See also server.
HTML
On the World Wide Web, the feature, built into HTML, that allows a text area, image, or other object to become a "link" (as if in a chain) that retrieves another computer file (another Web page, image, sound file, or other document) on the Internet.
The range of possibilities is limited by the ability of the computer retrieving the outside file to view, play, or otherwise open the incoming file.
It needs to have software that can interact with the imported file. Many software capabilities of this type are built into browsers or can be added as "plug-ins."
INTERNET
The vast collection of interconnected networks that all use the TCP/IP protocols and that evolved from the ARPANET of the late 60’s and early 70’s. An "internet" (lower case i) is any computers connected to each other (a network), and are not part of the Internet unless the use TCP/IP protocols.
An "intranet" is a private network inside a company or organization that uses the same kinds of software that you would find on the public Internet, but that is only for internal use. An intranet may be on the Internet or may simply be a network.
IP Address or IP Number
(Internet Protocol number or address). A unique number consisting of 4 parts separated by dots, e.g. 165.113.245.2 Every machine that is on the Internet has a unique IP address.
If a machine does not have an IP number, it is not really on the Internet. Most machines also have one or more Domain Names that are easier for people to remember.
Internet Service Provider
A company that sells Internet connections via modem (examples: aol, Mindspring - thousands of ISPs to choose from; not easy to evaluate).
Faster, more expensive Internet connectivity is available via cable, DSL, ISDN, or web-TV. Often these companies also provide Web page hosting service (free or relatively inexpensive web pages -- the origin of many personal pages).
JAVA
A network-oriented programming language invented by Sun Microsystems that is specifically designed for writing programs that can be safely downloaded to your computer through the Internet and immediately run without fear of viruses or other harm to our computer or files.
Using small Java programs (called "Applets"), Web pages can include functions such as animations, calculators, and other fancy tricks.
We can expect to see a huge variety of features added to the Web using Java, since you can write a Java program to do almost anything a regular computer program can do, and then include that Java program in a Web page.
For more information search any of these jargon terms in the PC Webopedia.
JAVASCRIPT
A simple programming language developed by Netscape to enable greater interactivity in Web pages. It shares some characteristics with JAVA but is independent. It interacts with HTML, enabling dynamic content and motion.
KEYWORD(S)
A word searched for in a search command. Keywords are searched in any order. Use spaces to separate keywords in simple keyword searching. To search keywords exactly as keyed (in the same order), see PHRASE.
LINK
The URL imbedded in another document, so that if you click on the highlighted text or button referring to the link, you retrieve the outside URL.
If you search the field "link:", you retrieve on text in these imbedded URLs which you do not see in the documents.
LINK "ROT"
Term used to describe the frustrating and frequent problem caused by the constant changing in URLs. A Web page or search tool offers a link and when you click on it, you get an error message (e.g., "not available") or a page saying the site has moved to a new URL.
Search engine spiders cannot keep up with the changes. URLs change frequently because the documents are moved to new computers, the file structure on the computer is reorganized, or sites are discontinued.
If there is no referring link to the new URL, there is little you can do but try to search for the same or an equivalent site from scratch.
META-SEARCH ENGINE
Search engines that automatically submit your keyword search to several other search tools, and retrieve results from all their databases.
Convenient time-savers for relatively simple keyword searches (one or two keywords or phrases in " "). See Meta-Search Engines page for complete descriptions and examples.
NESTING
A term used in Boolean searching to indicate the sequence in which operations are to be performed. Enclosing words in parentheses identifies a group or "nest." Groups can be within other groups. The operations will be performed from the innermost nest to the outmost, and then from left to right.
NEWSGROUP
A discussion group operated through the Internet. Not to be confused with LISTSERVERS which operate through e-mail.
PERSONAL PAGE
A web page created by an individual (as opposed to someone creating a page for an institution, business, organization, or other entity). Often personal pages contain valid and useful opinions, links to important resources, and significant facts.
One of the greatest benefits of the Web is the freedom it as given almost anyone to put his or her ideas "out there." But frequently personal pages offer highly biased personal perspectives or ironical/satirical spoofs, which must be evaluated carefully.
The presence in the page's URL of a personal name (such as "jbarker") and a ~ or % or the word "users" or "people" or "members" very frequently indicate a site offering personal pages.
PACKET, PACKET JAM
When you retrieve a document via the WWW, the document is sent in "packets" which fit in between other messages on the telecommunications lines, and then are reassembled when they arrive at your end.
This occurs using TCP/IP protocol. The packets may be sent via different paths on the networks which carry the Internet. If any of these packets gets delayed, your document cannot be reassembled and displayed.
This is called a "packet jam." You can often resolve packet jams by pressing STOP then RELOAD. RELOAD requests a fresh copy of the document, and it is likely to be sent without jamming.
PDF or .pdf or pdf file
Abbreviation for Portable Document Format, a file format developed by Adobe Systems, that is used to capture almost any kind of document with the formatting in the original. Viewing a PDF file requires Acrobat Reader, which is built into most browsers and can be downloaded free from Adobe.
PLUG-IN
An application built into a browser or added to a browser to enable it to interact with a special file type (such as a movie, sound file, Word document, etc.)
POPULARITY RANKING of search results
Some search engines rank the order in which search results appear primarily by how many other sites link to each page (a kind of popularity vote based on the assumption that other pages would create a link to the "best" pages). Google is the best example of this. See also Subject-Based Ranking.
+REQUIRE or -REJECT A TERM OR PHRASE
Insert + immediately before a term (no space) to limit search to documents containing a term. Insert - immediately before a term (no space) to exclude documents containing a term. Can be used immediately (no space) before the " " delimiting a phrase.
Functions partially like basic BOOLEAN LOGIC. If + precedes more than one term, they are required as with Boolean AND. If - is used, terms are excluded as with Boolean AND NOT. If neither + no - is used, the default if Boolean OR.
However, full Boolean logic allows parentheses to group and sequence logical operations, and +/- do not. Which search engines have this?
RELEVANCY RANKING of search results
The most common method for determining the order in which search results are displayed. Each search tool uses its own unique algorithm.
Most use "fuzzy and" combined with factors such as how often your terms occur in documents, whether they occur together as a phrase, and whether they are in title or how near the top of the text. Popularity is another ranking system.
SCRIPT
A script is a type of programming language that can be used to fetch and display Web pages. There are may kinds and uses of scripts on the Web. They can be used to create all or part of a page, and communicate with searchable databases.
Forms (boxes) and many interactive links, which respond differently depending on what you enter, all require some kind of script language. When you find a question marke (?) in the URL of a page, some kind of script command was used in generating and/or delivering that page.
Most search engine spiders are instructed not to crawl pages from scripts, although it is usually technically possible for them to do so (see Invisible Web for more information).
SERVER, WEB SERVER
A computer running that software, assigned an IP address, and connected to the Internet so that it can provide documents via the World Wide Web. Also called HOST computer. Web servers are the closest equivalent to what in the print world is called the "publisher" of a print document.
An important difference is that most print publishers carefully edit the content and quality of their publications in an effort to market them and future publications.
This convention is not required in the Web world, where anyone can be a publisher; careful evaluation of Web pages is therefore mandatory. Also called a "Host."
SERVER-SIDE
Something that operates on the "server" computer (providing the Web page), as opposed to the "client" computer (which is you or someone else viewing the Web page). Usually it is a program or command or procedure or other application causes dynamic pages or animation or other interaction.
SITE or WEB-SITE
This term is often used to mean "web page," but there is supposed to be a difference. A web page is a single entity, one URL, one file that you might find on the Web.
A "site," properly speaking, is an location or gathering or center for a bunch of related pages linked to from that site. For example, the site for the present tutorial is the top-level page "Internet Resources."
All of the pages associated with it branch out from there -- the web searching tutorial and all its pages, and more. Together they make up a "site." When we estimate there are 5 billion web pages on the Web, we do not mean "sites." There would be far fewer sites.
SPIDERS
Computer robot programs, referred to sometimes as "crawlers" or "knowledge-bots" or "knowbots" that are used by search engines to roam the World Wide Web via the Internet, visit sites and databases, and keep the search engine database of web pages up to date.
They obtain new pages, update known pages, and delete obsolete ones. Their findings are then integrated into the "home" database.
Mos