File sharing is the practice of distributing or providing access to digitally stored information, such as computer programs, multi-media (audio, video), documents, or electronic books. It may be implemented in a variety of storage, transmission, and distribution models. Common methods are manual sharing using removable media, centralized computer file server installations on computer networks, World Wide Web-based hyperlinked documents, and the use of distributed peer-to-peer (P2P) networking.

File sharing is not of itself illegal. However, the increasing popularity of the mp3 music format in the late 1990s led to the release and growth of Napster and other software that aided the sharing of electronic files. This in practice led to a huge growth in illegal file sharing: the sharing of copyright protected files without permission.

Although the original Napster service was shut down by court order, it paved the way for decentralized peer-to-peer file sharing networks such as Gnutella, Gnutella2, eDonkey2000, the now-defunct Kazaa network, and BitTorrent.

Many file sharing networks and services, accused of facilitating illegal file sharing, have been shut down due to litigation by groups such as the RIAA and MPAA. During the early 2000s, the fight against copyright infringement expanded into lawsuits against individual users of file sharing software.

The economic impact of illegal file sharing on media industries is disputed. Copyright holders and publishers refer to studies concluding that unauthorized downloading of movies, music and software is unequivocally damaging the economy, although other studies suggest file sharing is not the primary cause of declines in sales. Illegal file sharing remains widespread, with mixed public opinion about the morality of the practice.