The Internet Archive is a non-profit organization that offers permanent access for the general public to historical collections that exist in digital format. The Internet Archive includes collections of digitized materials, including websites, software applications and games, music, movies and videos, moving images, and nearly three million public-domain books. The Internet Archive allows the public to upload and download digital material , but most of its data is collected automatically by its web crawlers to preserve as much of the public web as possible. The Wayback Machine, a huge web archive, contains over 150 billion web captures.