User Roles

As Administrator, WordPress allows you to use User Roles section to set the permissions and access of the user.
You can access it from your Dashboard by clicking on Users > User Roles.
In User Roles section, you can create Role and determine which admin pages can be viewed and modified by each Role..
Note that you must know which pages can be accessed or modified with the Access and Modify permissions..
You have five pre-defined User Roles in your default WordPress Administrator and Editor and Author and Contributor and Subscriber.
While Administrator Role has all the permissions.
Click on Action button for one of User Roles to see the permission fields..
The Edit User Roles section gives you one field Permission, Administrator User Roles has all the permissions.
I am ready to answer on your questions about plugin usage.
Read more