Header bidding is less complicated than it sounds. Put simply, it’s a more efficient way for publishers to open of opening their inventory to more programmatic demand. It achieves this by offering the inventory to multiple exchanges simultaneously, rather than as a waterfall (where the inventory is offered out sequentially). One of the companies at the forefront of header bidding (although many vendors offer it) is Index Exchange, an SSP and premium exchange. Here Andrew Casale, Index Exchange’s President and CEO, explains how the process works, the impact it’s like to have on video and on the wider ecosystem. Interestingly, he also says that viewability rates rise when header bidding is implemented on a publisher’s site.