Glossary
What is Prebid Server?
Also called: PBS
Prebid Server is open-source software that runs header bidding on a server, so the page or app sends one request instead of calling every bidder.
हिंदी में पढ़ेंPrebid Server moves the header bidding auction off the reader’s device. With server-to-server (S2S) bidding, the page sends one request to Prebid Server, which calls the bidders and returns their bids. That lightens the load on the browser, and it is how apps, AMP pages and CTV take part in Prebid auctions.
The trade-off is identity. Bidders’ cookies live on their own domains, so a server cannot read them directly. Prebid Server relies on cookie syncing to match each bidder’s user ID with the ID the server-side system uses.
You do not have to choose one side. Prebid.js can send some bidders to Prebid Server and keep others in the browser. Prebid’s timeout guidance suggests setting the server timeout at roughly 50% to 75% of the overall auction timeout, so server bids return in time, and the hb_source key-value lets you report client-side and server-side results side by side.
Example
A page has 8 bidders. Moving 5 of them to Prebid Server leaves 3 browser calls plus 1 server request: 4 requests from the page instead of 8. With a 1,000 ms auction timeout, a server timeout of 500 to 750 ms follows Prebid's guidance.
Why it matters to publishers
Server-side bidding can lighten pages and bring apps and CTV into header bidding, but weaker cookie matching can affect bids, so test bidder by bidder.