Valve is the company that created Steam.

Valve was founded by Mike Harrington and Gabe Newell in 1996.

Valve are best known for award winning First Person Shooters.

Valves franchises include Half Life, Counterstrike, Left 4 Dead and Team Fortress.

Steam was released in 2004 with a Beta of Counterstrike Source with the title Half Life 2 becoming the first retail game to use steam

Valves Video games are considered some of the best in the world

http://www.valvesoftware.com/

VALVE CATALOG

Valve catalog includes any franchise that is developed by Valve.

These include:
Half life
Counter-Strike
Team Fortress
Garry's Mod
Portal
Left 4 Dead

http://www.valvesoftware.com/games/