It is now recognised that Britain has not always been geographically isolated from Europe and, for most of the last one million years, formed an extension of the northwest European landmass. During most of this time, Britain was accessible to migrating humans and animals, although climatic conditions varied greatly from Mediterranean-like through to glaciations and extreme cold, making Britain a difficult place to settle for any length of time. The oldest evidence for humans in Britain dates to between about 850,000 and 1 million years ago. Recovered lithic artefacts suggest that hominin species occupied and deserted the British Isles at least nine times. This article reviews the prehistory of the British Isles and presents the main sites and time periods