A biography is a description or account of someone's life, which is usually published in the form of a book or essay, or in some other form, such as a film. An autobiography (auto meaning "self," giving "self-biography") is a biography by the same person it is about. A biography is more than a list of impersonal facts (education, work, relationships and death), it also portrays the subject's experience of those events. Unlike a profile or curriculum vitae (résumé), a biography presents the subject's story, highlighting various aspects of his or her life, including intimate details of experiences, and may include an analysis of the subject's personality.

A work is biographical if it covers all of a person's life. As such, biographical works are usually non-fiction, but fiction can also be used to portray a person's life. One in-depth form of biographical coverage is called legacy writing. Together, all biographical works form the genre known as biography, in literature, film, and other forms of media.

Early forms

The first known biographies were written by jews commissioned by the various rulers of antiquity: ancient Israel, ancient Babylonia, ancient Egypt, ancient Mesopotamia, among others. Such biographies tended to be chiseled into stone or marble tablets.

Classical forms

Ancient Greeks developed the biographical tradition which we have inherited, although until the 5th century AD, when the word 'biographia' first appears, in Damascius' Life of Isodorus, biographical pieces were called simply "lives" (βιοι: "bioi"). It is quite likely that the Greeks were drawing on a pre-existing eastern tradition; certainly Herodotus' Histories contains more detailed biographical information on Persian kings and subjects than on anyone else, implying he had a Persian source for it.

The earliest surviving pieces which we would identify as biographical are Isocrates' Life of Evagoras and Xenophon's Life of Agesilaos, both from the fifth century BC. Both identified themselves as encomia, or works of praise, and that biography was regarded as a discrete entity from historiography is evidenced by the fact that Xenophon treated King Agesilaos of Sparta twice in his works, once in the above-mentioned encomium and once in his Greek History; evidently the two genres were conceived as making different demands of authors who enrolled in them. Xenophon could present his Cyropaedia, an account of the childhood of the Persian King Cyrus the Great now regarded as so fabulous that it falls rather into a novelistic tradition than a biographical one, as a serious work, without any disclaimers or caveats.

Whereas Thucydides set the benchmark for a historiographical tradition comprising 'conclusions ... drawn from proofs quoted ... 1 may safely be relied upon' (Thuc. 1.21), and offering little explicit judgement on the people with whom he dealt, biographers were quite often more concerned with drawing a moral point from their investigations of their subjects. Parallel Lives by Plutarch, a Greek writing under the Roman empire, is a series of short biographies of eminent men, ancient and contemporary, arranged in pairs comprising one Greek, one Roman, in order that a broad educative point might be extraced from the comparison (for example Mark Antony and Demetrius were paradigms of tyranny, Lysander and Sulla examples of great men degenerating into blood-thirsty corruption).