Programmatic · also called SSP, supply-side platform, sell-side platform
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.
A supply-side platform is the seller's counterpart to the DSP. It takes each ad request from a publisher's site, app or stream, turns it into a bid request, sends it to many DSPs and other buyers, runs the auction, and returns the winning ad. It also lets publishers set floors, create deals and PMPs, block unwanted advertisers or categories, and see reports.
Today the terms SSP and ad exchange are nearly interchangeable, since almost every SSP runs its own exchange. Well-known SSPs include Google Ad Manager's AdX, Magnite, PubMatic, Index Exchange, OpenX and many mobile-focused players. SSPs plug into header bidding wrappers such as Prebid and into app ad mediation.
SSPs are responsible for supply-chain honesty: they publish sellers.json, add themselves to the supplyChain object, and should screen out invalid traffic and made-for-advertising sites supply. They earn a take rate, typically a percentage of the price the buyer pays.
Think of it like this
An SSP is like an estate agent for ad space: it lists the property with every buyer at once, collects offers and takes a commission on the sale.
An example
A Japanese news app sends 50 million requests a day through two SSPs. One SSP clears 70% of them at an average US$1.80 CPM and keeps a 15% fee.
Related terms
DSP (demand-side platform)
A DSP (demand-side platform) is software that advertisers and agencies use to buy ad impressions automatically across many exchanges and publishers, deciding which impressions to bid on and how much.
Ad exchange
An ad exchange is a digital marketplace where buyers and sellers of ad impressions meet and trade through automated auctions, usually in real time.
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.
sellers.json
sellers.json is a public file in which SSPs and exchanges list their seller accounts, naming who owns each one and whether it is a publisher or an intermediary.
Take rate
Take rate is the percentage of the money flowing through an ad tech platform that it keeps as its fee: platform revenue divided by the gross spend it handles.