This handbook explores the economics of prostitution and offers a working definition of prostitution that takes into account both remunerated professional sex work, as in the case of the Nevada brothels, and the more informal exchange of sex for money that occurs in both developing and developed countries. The discussion is organized into six parts: supply and demand, sex workers in developing countries, men who have sex with men, law and policy, history of prostitution law, and externalities related to sex markets (e.g., sexually transmitted infections and sexual exploitation). Topics range from economic theories and empirical analysis of sex markets to sexual and communication networks of Internet-mediated prostitution, to the spread of sexually transmitted infections and violence.