DSP ( Demand Side Platform )
Media buying has come a long way from traditional mass-purchasing; it has evolved from buying ads directly from publishers, to purchasing through aggregators such as ad networks, to going through real-time exchanges that act much like financial markets. The most modern form of automated or programmatic media buying (i.e., no insertion orders or contracts) is made possible by the technology known as real-time bidding (RTB).
RTB allows the automation of the media buying process that up to now has largely been manual. This makes online advertising easier, less labour-intensive, less error-prone, and more efficient for both agencies and publishers in setting up and running a campaign. Costs are reduced, thereby improving profitability.
Demand-Side Platforms (DSPs), like the Netstreamed RTB, are companies that advertisers use to create RTB campaigns. You can imagine a DSP as essentially an ad server that has been directly integrated into traffic sources.