The document discusses DSPs (demand side platforms), RTB (real-time bidding), and programmatic buying. It explains how DSPs emerged to control buying and data in response to arbitrage in the digital ad marketplace. DSPs use 1st and 3rd party data along with verification tools to target ads through real-time bidding, guaranteed premium placements, and direct site buys. Challenges discussed include low-quality inventory, excessive retargeting, and optimizing systems based on the wrong metrics like clicks instead of conversions. The document also outlines options for outsourcing programmatic buying and special platforms for mobile and video ads.