An autobiography is a book about the life of a person, written by that person.
The word autobiography was first used deprecatingly by William Taylor in 1797 in the English

English language

English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

 periodical

Periodical publication

Periodical literature is a published work that appears in a new edition on a regular schedule. The most familiar examples are the newspaper, often published daily, or weekly; or the magazine, typically published weekly, monthly or as a quarterly...

 the Monthly Review

Monthly Review (London)

The Monthly Review was an English periodical founded by Ralph Griffiths, a Nonconformist bookseller. The first periodical in England to offer reviews, it featured the novelist and poet Oliver Goldsmith as an early contributor. William Kenrick, the "superlative scoundrel", was editor from 1759 to...

, when he suggested the word as a hybrid but condemned it as 'pedantic'; but its next recorded use was in its present sense by Robert Southey

Robert Southey

Robert Southey was an English poet of the Romantic school, one of the so-called "Lake Poets", and Poet Laureate for 30 years from 1813 to his death in 1843...

 in 1809. The form of autobiography however goes back to antiquity.