A bidder number (also called a “paddle” from the physical numbered paddle held up at live sales) is the unique identifier assigned to a registered bidder for a given auction. The auctioneer calls out paddle numbers when recognizing a bid: “I’m bid five hundred from forty-two.”
Paddle assignment requires registration — usually with a credit card on file and ID verification. Numbers reset for each auction in some venues; others issue permanent buyer numbers tied to a CRM. Online auctions usually display the bidder’s username (anonymized) instead of a number, but the underlying data structure is the same.
The physical paddle — a numbered card on a stick — is one of the oldest tools in the auction industry. Modern paddles are usually printed cardstock, but high-end auction houses still issue laminated or branded paddles as a brand touch. Lost paddles are a routine headache for clerks. If a bidder loses their paddle mid-sale, the auction has to track them down before settlement to confirm what they actually won. For this reason, most modern auctions also collect mobile phone numbers at registration so winning bidders can be confirmed by text message.