The Steam platform is the largest digital distribution platform for PC gaming, estimated in 2013 to have 75% of the market space.
In 2015, users purchasing titles through Steam or through Steam keys from third-party vendors totaled roughly $3.5 billion, representing 15% of the global PC game sales for the year, based on estimations made by the tracking website Steam Spy.
Canadian publisher Strategy First announced in December 2005 that it would partner with Valve for digital distribution of current and future titles.
Valve's Half-Life 2 was the first game to require installation of the Steam client to play, even for retail copies.
Steam provides the user with installation and automatic updating of games, and community features such as friends lists and groups, cloud saving, and in-game voice and chat functionality.