Auction is a sort of a place for players and draft picks trade. Only players with trade value higher then 80 can be auctioned off as well as first-round draftpicks. 

Auction rules

Minimal starting price of an object being auctioned off is defined by its owner. Any object is auctioned for 3 days. Minimal increment is 1000. If the bet was placed less then 10 minutes before the end of the auction, it is prolonged for 10 more minutes.