Header Bidding / Prebid - Display Ads

Header Bidding: Placing script in head of site, that renders Ad in Ad Spaces before page loads
Header Bidder: Tech/Tools used in bidding [code publishers put in their web-app’s header

Publishers install a snippet of js(called a header bidding wrapper) in the header of their website.
Each time a user visits a page, the header bidding wrapper triggers the header bidding process.
In the milliseconds before the page loads, the ad auction takes place, the winning bid is determined, and the ad creative is displayed for the user.
Publishers can set rules for profit — such as how long advertisers have to place their bid