When bidding for goods and services, there are two primary types: sealed bids and open auctions. Sealed bids involve submitting a written offer that is kept confidential; these bids are then opened simultaneously and compared against one another. On the other hand, open auctions involve open competition between bidders. These may occur in person or online. In an open auction, each bidder can see what others are offering. Whichever bid offers the best value will typically win out in either situation.