I'm talking about magento stores generally, and specifically for the magento uMarketplace extension.
What I'm talking about is giving different users different permissions that control which resources they can access on a store. Below I give two different examples. The first is Amazons AWS Identity Access management (IAM), but for users who signed up for a domain that is running a marketplace thanks to uMarketplace
Example 1:
AWS Identity and Access Management is a web service that enables Amazon Web Services (AWS) customers to manage users and user permissions in AWS. The service is targeted at organizations with multiple users or systems that use AWS products such as Amazon EC2, Amazon RDS, and the AWS Management Console. With IAM, you can centrally manage users, security credentials such as access keys, and permissions that control which AWS resources users can access. http://docs.aws.amazon.com/IAM/latest/UserGuide/IAM_Introduction.html
Example 2:
Lets take eBay for example. Jason who owns Johns Big Trucks auto dealership wants his auto dealership to sell cars on eBay. Jason also doesn't want to have to share the only accounts username and password for security reason, but he wants to give his employees accounts so they can list cars for sale and do the accounting so he doesn't have to do it. So, Jason wants to use his root account to create a child account for John's Big Trucks that give each user different abilities to manage different parts of John's Big Truck store on ebay. Jason's account will have the ability add and delete employee child accounts as he hires and fires them promotes them etc. Two examples of different types of access is giving an employee who can only sell cars and edit that information but not giving them access the the billing; and another type of account is the complete reverse. Jason wants to give Johns Big Trucks accountant only access to the billing, returns, and not the ability to list new cars for sale.