This paper provides an elementary, non-technical survey of auction theory, introducing and describing key papers in the field. It begins with fundamental concepts and then covers optimal auctions, revenue equivalence, and marginal revenues. Subsequent sections address risk-aversion, affiliation, asymmetries, entry, collusion, multi-unit auctions, double auctions, royalties, and other topics. Appendices contain technical details, examples, and bibliographies. Auctions are important for practical, empirical, and theoretical reasons. They are used in many economic transactions, including government sales, procurement, and private sales. Auctions provide a testing ground for economic theory, especially game theory with incomplete information. They are also fundamental to understanding price formation and monopoly pricing. The paper discusses four basic auction types: ascending (open), descending (Dutch), first-price sealed-bid, and second-price sealed-bid (Vickrey). It explains the basic models of auctions, including private-value and common-value models. It also discusses bidding strategies in these auctions, the winner's curse, and the equivalence of different auction types under certain conditions. The paper covers risk aversion, correlation, affiliation, asymmetries, entry, collusion, multi-unit auctions, double auctions, and other topics. It discusses the revenue equivalence theorem, which states that different auction types yield the same expected revenue under certain conditions. It also discusses marginal revenues and how they relate to auction design. The paper discusses the effects of relaxing assumptions in auction models, such as risk-aversion, correlation, and asymmetries. It also discusses the design of optimal auctions, the role of reserve prices, and the effects of collusion. It concludes with a discussion of the importance of auction theory in understanding economic transactions and its applications in various fields.This paper provides an elementary, non-technical survey of auction theory, introducing and describing key papers in the field. It begins with fundamental concepts and then covers optimal auctions, revenue equivalence, and marginal revenues. Subsequent sections address risk-aversion, affiliation, asymmetries, entry, collusion, multi-unit auctions, double auctions, royalties, and other topics. Appendices contain technical details, examples, and bibliographies. Auctions are important for practical, empirical, and theoretical reasons. They are used in many economic transactions, including government sales, procurement, and private sales. Auctions provide a testing ground for economic theory, especially game theory with incomplete information. They are also fundamental to understanding price formation and monopoly pricing. The paper discusses four basic auction types: ascending (open), descending (Dutch), first-price sealed-bid, and second-price sealed-bid (Vickrey). It explains the basic models of auctions, including private-value and common-value models. It also discusses bidding strategies in these auctions, the winner's curse, and the equivalence of different auction types under certain conditions. The paper covers risk aversion, correlation, affiliation, asymmetries, entry, collusion, multi-unit auctions, double auctions, and other topics. It discusses the revenue equivalence theorem, which states that different auction types yield the same expected revenue under certain conditions. It also discusses marginal revenues and how they relate to auction design. The paper discusses the effects of relaxing assumptions in auction models, such as risk-aversion, correlation, and asymmetries. It also discusses the design of optimal auctions, the role of reserve prices, and the effects of collusion. It concludes with a discussion of the importance of auction theory in understanding economic transactions and its applications in various fields.