'Identity' as a concept has many faces, and its very versatility in different contexts can make it hard to define. Florian Coulmas discusses the many meanings of this slippery concept, considering why individual and collective identities are important to us, and discussing the problems asserting individual identities can create. Coulmas' masterful coverage of a diverse range of literature, from philosophy, law and psychology to linguistics, anthropology, and politics, makes this short introduction a treasure trove for anyone who wishes to understand or research issues of identity in history as well in the contemporary world. An invaluable guide to a fascinating field.