Revenue equivalence is a principle in economics that states that different auction formats can lead to the same expected revenue for sellers, provided certain conditions are met. These conditions include that bidders are rational, have independent valuations, and that the auction is open to all potential buyers. In simpler terms, whether a seller uses a first-price auction, second-price auction, or any other format, the total revenue generated should be similar if the auction is designed correctly. This concept helps economists understand how different auction types can be equally effective in maximizing seller profits.