Steam is a program from Valve, essential to run some of its games. It is at the same time an instant messenger, net store and copy protection. Steam allows you to keep track of what its games you play and how long you play them. There is also a built-in web browser, used mainly for account management and shopping.

Steam also features a game overlay, that can be used with all Steam-linked games to chat with your Steam-friends, join servers or browse the web without having to Alt-TAB to windows. You can link almost any game or program to Steam, allowing you to use the game overlay in them. Steam itself is free, and requires a Steam-account.