Valve Corporation is an American video game developer and digital distribution company headquartered in Bellevue, Washington. The company is known for its software distribution platform Steam and the Half-Life, Counter-Strike, Portal, Day of Defeat, Team Fortress, Left 4 Dead, and Dota 2 games.

Valve was founded in 1996 as a limited liability company by former Microsoft employees Gabe Newell and Mike Harrington. Their debut product, the PC first-person shooter Half-Life, was released in 1998 to critical acclaim and commercial success, after which Harrington left the company.

Valve launched Steam in 2003 by 2011, over half of digital PC game sales were through Steam, and Valve was the most profitable company per employee in the United States. In 2015, Valve entered the game hardware market with the Steam Machine, a line of prebuilt gaming computers running Valve's SteamOS operating system.