Ad-tech
Header bidding
Publisher-side auction that calls multiple SSPs in parallel before AdServer.
Header bidding is a publisher-side auction technique where multiple SSPs (Prebid, AdX, Amazon, AppNexus, Criteo) are called in parallel from the page header, each returns a bid, the highest bid is passed to the ad server. Replaces 'waterfall' (sequential SSP calls) which historically under-monetized publishers. Header bidding lifts publisher RPMs 20–40% on average. Standard implementation: Prebid.js wrapper.
Example
Publisher running waterfall at $4.10 RPM switches to Prebid header-bidding with 7 SSPs — RPM rises to $5.85 over 30 days as competition between SSPs lifts cleared CPM.