This lecture series will present the main directions of Algorithmic Game Theory, a new field that has emerged in the last two decades at the interface of Game Theory and Computer Science, because of the unprecedented growth in size, complexity, and impact of the Internet and the Web. These include the price of anarchy (what is the impact of selfishness on a system of competing entities), computational complexity (can the market find a reasonable solution), mechanisms and auctions (what incentives to give to selfish individuals).