Below are the different types of auctions that are available on eBay.

Reserve Prices

Auctions may be run with reserve prices. The reserve price is the lowest price at which a seller is willing to sell an item. The reserve price is not disclosed to bidders. A seller might specify a reserve price if he or she is unsure of the real value of the item and would like to be able to refuse to sell the item if the market value is below a certain price. During an auction, an annotation will be displayed in the item information screen if the seller has specified a reserve price.

The seller specifies the reserve price when he or she lists an item. This price should be above the minimum bid price. The auction begins at the minimum bid price. When a bidder's maximum bid is equal to or greater than the reserve price, the item's current price is raised to the reserve price. At this time, the item information will indicate the reserve price has been met. The bidder is also notified that his or her bid met the reserve.

If the reserve price is not met, neither the seller nor the high bidder is under any further obligation.

On eBay.co.uk, sellers who wish to use a reserve price must set the reserve price to be equal to or greater than £50. It is not permissible to set a reserve price level to be less than £50.

Please note that reserve price auctions are not available for Dutch auctions, and items with reserve prices are not displayed in the hot items section.

Private Auctions

A seller may specify that an auction will be a private auction. This means bidders' email addresses will not be disclosed on the item screen or bidding history screen. Only the seller and the high-bidder will be notified via email when the auction is over. This option is useful when the seller realises that potential bidders may not want their identities disclosed to the general public. This option is not available for Dutch auctions.

Dutch Auctions

Dutch auctions are a special auction format where a seller has multiple, identical items he or she wishes to sell. The seller specifies the minimum price (the starting bid) and the number of items available. Bidders bid at or above that minimum for the quantity they are interested in purchasing. At the close of the auction, the highest bidders purchase the items at the lowest successful bid.

For example, imagine there are 10 TVs being sold at £100. 25 people bid £100 for one TV each. In this case, only the first 10 people will be the successful bidders, since the bid amounts are the same, and earlier bids take precedence.

Now, say that one of those people bid £150 for one TV. Since her bid is higher than all the others, she will certainly be one of the successful bidders. The other 9 TVs will be claimed by the earliest bidders who bid £100, and the final price for each TV will be £100.

If enough people bid above the minimum bid, the final price of the item will increase as well. On the other hand, if less than 10 people bid in our example, then only that number of TVs will be sold at the opening price of £100. For the selling price to increase past the opening price specified by the seller, there must be an equal or higher level of demand than the supply indicated. In our example, the selling price would only increase if 11 or more TVs were bid upon, no matter what the amount of each bid.

In the case of multiple quantities bid for by a bidder, the lowest bidder may not earn the right to purchase the complete quantity, since there may only be one left by the time the higher bidders have been processed. In other words, if the lowest bidder requested a quantity of 3 TVs, she might only be entitled to one TV, since 9 other TVs could be allocated to higher bidders. The only way around this problem is to ensure that you are not the lowest bidder. In some cases, a bidder may reserve the right to refuse purchase of a partial quantity. In that case, the seller may skip that bidder and move on to the next one, if any.

In Dutch auctions, the current standings are always displayed after the item description, and the complete bidding history (including unsuccessful bids) is available as well.