Programmatic · also called Prebid.js, Prebid Server, Prebid Mobile
Prebid
Prebid is the most widely used open-source header bidding software, including Prebid.js for websites, Prebid Server for server-side auctions and Prebid Mobile for apps.
Prebid is free, open-source code that lets publishers run header bidding auctions among many demand partners. It started in 2015 as Prebid.js, released by AppNexus, and is now governed by the independent Prebid.org organisation, with contributions from SSPs, publishers and other ad tech firms.
The main products are Prebid.js (a JavaScript library that runs in the browser), Prebid Server (runs auctions on a server, for server-side header bidding, apps and CTV), and Prebid Mobile SDKs. Each SSP or bidder writes an "adapter" so Prebid can talk to it, and there are hundreds of adapters. Modules add identity solutions, consent handling for IAB TCF and IAB Global Privacy Platform, floors, supplyChain object support and real-time data providers, including invalid-traffic filters.
Because it is open and vendor-neutral, Prebid became the default alternative to relying only on Google's auction. Do not confuse the software (Prebid) with the organisation that maintains it (Prebid.org).
Think of it like this
Prebid is like a free, community-built auction hall that any seller can set up in their own shop, with plug-in microphones for each bidder.
An example
A publisher adds adapters for five SSPs and sets a 1,000 ms bidder timeout in Prebid.js; average revenue per page rises after the old waterfall is switched off.
Related terms
Prebid.org
Prebid.org is the independent, member-funded organisation that governs and maintains the open-source Prebid header bidding projects, including Prebid.js, Prebid Server and Prebid Mobile.
Header bidding
Header bidding is a technique where a publisher offers each ad impression to many SSPs and exchanges simultaneously before calling its ad server, so all buyers compete at once.
Server-side header bidding
Server-side header bidding runs the header bidding auction on a remote server rather than in the user's browser or app, reducing page weight and latency while connecting to more bidders.
Auction timeout
An auction timeout is the maximum time an auction waits for bids; responses that arrive after it are ignored, even if they would have won.
SSP (supply-side platform)
An SSP (supply-side platform) is software that publishers use to sell their ad inventory automatically to many buyers, running auctions and managing prices, deals and quality controls.
Sources: Prebid documentation