Supply-Side Platform (SSP)
A platform used by publishers to manage, offer and optimize digital advertising inventory across buyers and exchanges.
An SSP lets publishers sell inventory to many demand sources at once, set price floors and rules, and control which advertisers appear, which directly affects ad revenue and brand safety.
A news publisher connects its ad server to two SSPs, sets a $2.50 CPM floor on homepage leaderboard units, blocks gambling advertisers and compares fill rate and effective CPM per SSP each month.
Each SSP and reseller in the chain takes a fee, and duplicate paths to the same impression add cost and confusion for buyers. Publishers have limited visibility into how exchanges run auctions and apply discounts.
An SSP receives ad requests from the publisher's ad server or a header bidding wrapper, packages them as OpenRTB bid requests, sends them to connected exchanges and DSPs, runs the auction against floors and deal rules, and returns the winning creative. Publishers list authorized SSPs in ads.txt, and SSPs publish sellers.json and pass the SupplyChain object so buyers can trace each seller.
Data Engineering, Systems Architecture
Amazon Ads — DSP vs SSP: What is the difference? — https://advertising.amazon.com/library/guides/dsp-ssp-dmp-difference; IAB Tech Lab — sellers.json Supply Chain Transparency — https://iabtechlab.com/sellers-json/