After a paid sale, buyers and sellers rate each other with one to five stars and a comment. The average rating and the number of ratings appear on every item page and on the public seller profile.
Buyers don't bid on unknown sellers. Ratings give every seller a public reputation, and good sellers quickly become the reason buyers return to your site.
Sellers see the rating of a buyer before they accept an offer, which protects them from unreliable bidders.
The administrator can review and remove unfair feedback in Admin > Sales > Feedback.