In the age of the Internet, personal, open interaction and the corresponding implicit trust are impossible. Websites instead have to figure out how to approximate the level of intimacy and reputation that humans are conditioned to expect. How do site owners go about this process? How do websites like eBay convince people to exchange their money with anonymous strangers? How does Wikipedia, a mostly uncurated encyclopedia that anybody at all can edit, gain the trust of hundreds of millions of readers? In this section, we discuss the current state of reputation systems along with their successes and their failures.