Auctions are public sales of good, conducted by an officially approved auctioneer. He asks the crowd assembled in the auction-room to make offers, or "bids", for the various items on sale. He encourages buyers to bid higher figures, and finally names the highest bidder as the buyers of the goods. This is called "knocking down" the goods, for the bidding ends when the auctioneer bangs a small on a table at which he stands. This is often set on a raised platform called a rostrum.