Header bidding is a way to set up several networks to allow them to compete against each other for inventory on the site. A timeout is set which pauses the initial call to the ad server to allow the bidders to get their bids in. The highest paying bid is then sent to the ad server at which point Google Ad Exchange (AdX) or any other ads compete against it. The ad server ultimately picks the winner and the ad is served on the page.
Header bidding allows publishers to maximize their revenue as the various rates that come in will always be competing against each other to drive up overall revenue for the site. Freestar utilizes Prebid.js to handle the header bidding as it’s a widely used open source project that is actively being improved upon by a community of developers and ad tech engineers.