OpenRTB

The IAB Tech Lab protocol that defines the structure of bid requests and bid responses between SSPs, exchanges, and DSPs: what an impression is, what the page or app is, what the user is (where permitted), what formats are accepted, and what the bid is. Version 2.6 is the widely deployed release; 3.0 introduced a separate object model. Nearly every programmatic transaction outside the walled gardens runs on it.