bidding

The bidder at a house auction is making a public offer for the house in response to the auctioneer's invitation to treat. Because the bid is an offer only, it can be retracted at any time before the fall of the hammer. It does not matter how a bid is made as long as it is an effective bid. However, on the fall of the hammer there is a binding contract between the owner and the successful bidder. Therefore, a buyer cannot be gazumped under the auction process.

Generally if notified. the owner or his agent (dummy bidder) has a right to bid at the auction. However, many states/territories have introduced a more restrictive auction system with stricter controls on bidders. In nSW a bidder must register with the agent before allowed to bid.