Absolute Auction:
An Auction where the property is sold to the highest qualified bidder with no limiting conditions, contingencies or amounts.
Reserve Auction:
This is an auction in which the item for sale has a reserve price. The reserve price is the lowest price at which a seller is willing to sell an item. Although the reserve price is not listed per se (the auction posting will be marked as "reserve met"), it can be extrapolated when a bidder bids at or above the reserve price. The high bid will automatically be elevated to the reserve price, providing the current high bidder with what the seller would agree to sell at.
Straight Auction:
Also referred to as an absolute auction, this is an auction in which there is only one item up for sale, and there is no reserve price. The seller sets the opening bid and must respect the final price at the end of the auction.
Dutch Auction:
This is an auction in which the seller lists multiple quantities of an identical item. With multiple items up for sale, multiple bidders can win. Also, one bidder can try to buy more than one quantity. All winning bidders pay only the lowest successful winning bid amount.
Yankee auction:
Each winning bidder pays his or her exact high bid.
Timed Auction:
Bidders may only leave absentee bids which will be executed by the auctioneer after the listed ending time of the auction. A "Timed" auction does not have a live audience participating, therefore you will leave your maximum bid which is only increased when you are out bid. The current high bid will be made public on the item listing, but your identity will remain anonymous to both other bidders and the auction house. If your absentee bid is the high bid then you will be contacted by the auctioneer as the successful buyer.