Taboo refers to a proscription of behaviour for a specifiable community of one or more persons at a specifiable time in specifiable contexts. For behaviour to be proscribed it must be perceived as in some way harmful to an individual or their community but the degree of harm can fall anywhere on a scale from a breach of etiquette to out-and-out fatality. All tabooed behaviours are deprecated and they lead to social if not legal sanction. Shared taboos are a sign of social cohesion. This chapter surveys the history of taboo, fatal taboos, uncleanliness taboos, exploitation of taboos, swearing, censoring, taboo as a source of language change, and finally reviews the content of this handbook.