Real-time Bidding (RTB) is a way of transacting media that allows an individual ad impression to be put up for bid in real-time. This is done through a programmatic on-the-spot auction, which is similar to how financial markets operate. RTB allows for Addressable Advertising; the ability to serve ads to consumers directly based on their demographic, psychographic, or behavioral attributes.
The Real-Time Bidding (RTB) Project, formerly known as the OpenRTB Consortium, assembled technology leaders from both the Supply and Demand sides in November 2010 to develop a new API specification for companies interested in an open protocol for the automated trading of digital media across a broader range of platforms, devices, and advertising solutions.