Auction vs tender: auction uses public successive bidding to highest bidder; tender is an invitation to submit sealed offers for evaluation. An auction is a public disposal by successive bids where participants outbid one another and the sale usually goes to the highest bidder. A tender is an invitation to receive offers and operates as an offer to negotiate: bids are submitted in documents without knowledge of rival offers, precluding repeated outbidding and serving to ascertain acceptable offers within margins set by the offeror.