There are up to four main types of auction during a convention
- the Art Auction
- a general "Book" auction (people bring in boxes of books they would like to get some money for, either for themselves or a nominated "good cause/charity" and the convention auctioneers sell them for whatever they can get). In recent years this has either been dropped from the programme, or it's been the rarer books and/or raising money for a particular cause.
- Fannish Good Cause auctions. There are a number of fannish "good causes" such as the TransAtlantic Fan Fund (TAFF) which was set up to let fans from either side of the Atlantic get to fannish events on the other side. In the days of expensive airfares it was the only way that most Fans could afford to get across the pond. Nowadays it is less "necessary" but helps to keep a good mix going, particularly among the fanzine fans who might not otherwise travel much.) The TAFF (and GUFF (Getting Under/Getting Up from Under Fan Fund, for antipodean fans)) auctions tend to be much more eclectic (including things like chocolates, fun jewelry, the chance to have your name as a character in a book, silly tourist items etc.)
- Dead Dog Auction where supplies and equipment that were purchased for the convention, and are now finished with, are sold off to help pay for the convention or to raise funds to pass on to the following years' Eastercons.