A Brief History of Time is a popular science book written by Professor Stephen Hawking and first published in 1988. It rapidly became a best-seller, and had sold 9 million copies by 2002.

It attempts to explain a range of subjects in cosmology, including the Big Bang, black holes, light cones and superstring theory, to the nonspecialist reader. Its main goal is to give an overview of the subject but, unusually for a popular science book, it also attempts to explain some complex mathematics.

The author notes that for every equation in the book the readership will be halved, hence it includes only a single equation: E=mc².

A recent edition is ISBN 0553380168.