This document discusses using reputation mechanisms to establish trust online without physical interaction between parties. It notes that current approaches try to make dishonest transactions impossible but are impractical. Alternatively, reputation systems publish ratings and make dishonest behavior unappealing by damaging future reputation and business. Existing systems have issues, but second-generation systems aim to incentivize truthful reporting and establish reliable reputations using game theory, allowing trust in applications like e-commerce, monitoring, and inspection.