What is header bidding? 

Header bidding is a programmatic method of selling advertising space where publishers auction inventory to multiple ad exchanges and the ad exchanges bid for the highest price — all in real-time. Header bidding is sometimes referred to as advanced bidding or pre-bidding. Header bidding allows publishers to increase their yield and revenue.

Header bidding relates to websites, while in-app bidding is the programmatic selling and buying of ads via a real-time auction within mobile applications

What are the benefits of header bidding?

Header bidding helps publishers earn the highest revenue for their inventory and ensure that more ad space is sold. It achieves this by creating an auction where ad networks compete for ad space.

In addition, advertisers can use impression data first to optimize future campaigns. Header bidding also gives more advertisers access to premium inventory that otherwise may have been limited to fewer advertisers if sold traditionally.

Before programmatic advertising, the waterfall method was the most popular method of selling ad space.