OpenRTB is a set of open standards and protocols that are used in the real-time bidding (RTB) market for online advertising. OpenRTB was developed by the Interactive Advertising Bureau (IAB) to provide a common, standardized platform for buying and selling ads in real-time, and to enable advertisers and publishers to participate in RTB auctions and marketplaces. OpenRTB defines a set of APIs and protocols that enable advertisers and publishers to communicate and exchange information in real-time, such as ad impressions, bids, and wins. OpenRTB also defines a set of data formats and types that are used to represent and exchange information about ads, users, and context. OpenRTB is an important part of the RTB ecosystem, as it enables advertisers and publishers to participate in RTB auctions and marketplaces in a seamless and efficient way.