It is essentially an algorithm used by demand-side platforms to streamline how they interact with supply-side platforms. Each DSP has developed its own strategy for supply-path optimization: Some use it to pick up the bids that are most relevant and have the highest chance of winning, while others use it to turn off SSPs that are not implementing second-price auctions, according to Tom Kershaw, CTO for ad exchange Rubicon Project.
Read more here: https://digiday.com/media/what-is-supply-path-optimization/
