A solution to one of the biggest sources of market failure: asymmetric information. Often the biggest problem facing sellers is how to convince buyers that what they are selling is as good as they say it is. This problem arises in situations where the qualities of the thing being sold cannot be observed easily by buyers, who thus fear that sellers may be conning them. In such situations, an answer may be for sellers to do something that shows they mean what they say about quality. This something is what economists call signaling. Going to a leading university might be worth far more for what it signals to prospective employers about your abilities than for what you learn as a student. Likewise, the fact that a firm is willing to spend a lot of money advertising its product may say far more about what it thinks of the product than any information included in the actual ad. To be useful, signals must impose more costs on those who use them to send false messages than any gains to be had from lying.