What is a seat?
A seat is a paid user slot that provides edit rights to projects. Paid seats may be occupied by Team Members or Contributors.
Individual members within a team can take on a variety of roles: Admin, Manager, Member, and Reviewer. Admins, Managers, and Members all take up paid seats in the plan. Reviewers do not take up seats – unless they are granted edit rights.
There are also two kinds of outside collaborators that can have access to projects: Contributors can be granted editing rights and take up a seat, whereas Guests can only view and comment and do not.