A Brief Prehistory:
Header bidding is a response to the “waterfall” method, a fragmented and highly inefficient process for implementing programmatic advertising. Instead of offering impressions to one partner at a time, header bidding lets all partners bid simultaneously. With header bidding, publishers can also receive bids that may be unavailable through their primary ad server.
Prebid is born:
Prebid.js launched in 2015 to make header bidding easy for publishers by bringing conformity and simplicity to the header bidding process. By creating a simple, open tech layer upon which companies could add their code to a standard but optimized foundation, Prebid.js made it easier to implement header bidding, and offered the largest repository of working adapters.
Today, Prebid.js is the most widely used header bidding “container” or “wrapper” on the web.