Roles

Roles are used to control access to Tasks as well as the View Control. As many roles as needed can be created. Determining the users for roles is done through the ABAP exit Determine approvers for Roles.

You can make the configuration of User to Roles simpler by Creating an Approval Matrix Configuration App

Standards / conventions / best practice guide

You can name roles specifically created for your solution as you see fit (like "Approver" below), but refrain from using spaces - use underscores instead.
Do not rename System Roles.
In future releases, these will not be editable but until this measure is in place please refrain from changing the System Role names. You may experience unintended outcomes in the event that you do.