A sealed-bid auction is a type of auction where all bidders submit their bids privately and simultaneously. Each participant writes down their offer without knowing what others have bid. Once all bids are submitted, the auctioneer opens them, and the highest bidder wins the item or service being auctioned. This auction format is often used for selling government contracts, real estate, or valuable items. It encourages bidders to submit their best offer since they cannot adjust their bids based on competitors' actions. Sealed-bid auctions can help ensure a fair and competitive bidding process.