If a seller places an item on the eBay website in the “auction” format, he is making a binding offer to conclude a contract for this item. The provider determines a starting price and a deadline (offer duration) within which the offer can be accepted by bid. The bidder accepts the offer by submitting a bid using the bidding function. The bid expires if another bidder submits a higher bid during the offer period. When the auction ends or the offer is terminated prematurely by the provider, a contract for the purchase of the item is concluded between the provider and the highest bidder, unless the provider was legally entitled to withdraw the offer and delete the existing bids. After a legitimate bid withdrawal, no contract is concluded between the member who is the highest bidder again afte.