Valve Corporation (also known as Valve Software or simply Valve) is an American video game development and digital distribution company made famous by its highly successful and critically acclaimed first product, Half-Life. It is also well known for its social-distribution network Steam, and for developing the Source engine, which has been used in every product since its introduction in 2004.
About (from Valve at www.valvesoftware.com)
“We started with Half-Life®, the first-person, sci-fi shooter game that’s won more than 50 Game of the Year and a few 'Best Game Ever' awards. We expanded the Half-Life franchise with a sequel and Half-Life 2 Episodes 1 and 2. Then we added the horror”