Reference library · Inventory pricing
DSP (Demand-Side Platform)
A demand-side platform (DSP) is the software a buyer uses to bid on and buy digital ad inventory programmatically, connecting to multiple ad exchanges and supply-side platforms through one interface. It executes real-time bidding against the buyer's targeting, budget and pacing rules, and reports impressions, spend and win rate back per exchange. Planners route budget through a DSP to reach chosen audiences and inventory without negotiating with each publisher directly.
Worked example
A buyer sets up a DSP campaign for a mid-size retailer in the Czech Republic: a €40,000 flight budget over 20 days, a €3.50 CPM bid cap, targeting women 25-44 via a third-party data segment, capped at 4 impressions per user per week. Three days in, delivery is only €1,200/day against a €2,000/day pace target, and win rate on the exchange is 18%. The buyer raises the bid cap to €4.20 CPM; win rate climbs to 41% and daily delivery reaches €2,050, putting the flight back on pace to fully spend the €40,000 by day 20.
How it is used
A DSP is configured, not calculated: the buyer sets a bid strategy (fixed CPM cap, or auto-optimize to a CPA/CPC goal), a budget with daily and flight caps, frequency caps, and targeting (audience segments, contextual signals, geo, deal IDs for private marketplaces). The platform bids in real time across connected exchanges and reports delivered impressions, win rate and effective CPM back to the buyer. In practice, planners use the win-rate and delivery-pacing reports to diagnose underdelivery, and adjust bid caps or loosen targeting rather than pausing and relaunching the line item.
The common mistake
Diagnosing underdelivery as a targeting problem when the bid cap is sitting below the exchange's clearing price.