Steam is a digital distribution platform created by Valve to deliver gaming content to users over the internet. Notable aspects of the program include its wide catalogue of games available for purchase, social networking features, and relatively unobtrusive DRM system.

While Steam was initially tested with the game Counter-Strike, it wasn't until the release of Half-Life 2 that the platform gained widespread use. All copies of Half-Life 2 required registration through Steam to play, whether it was bought through Steam or at retail. Since then, all Valve games have utilized Steam as a content management and delivery system, with patches and games easily downloaded in the background while the computer is running.

The games available on Steam range from Valve-produced games to those published by most major software companies (such as EA or Activision). Games available on Steam are bound to the user's account name rather than the system itself. This allows users to download and play their games after a system failure or upgrade. These games can also be backed up for transfer to another computer and will automatically update when patches are available. Games not available on Steam can be added to the My Games list by browsing for the executable, allowing somebody to run all their games through Steam rather than loading them individually. Games not tailored for steam will allow in-game messaging, but not achievements or progress tracking.

Through Steam's social networking system users can maintain a list of friends that can be messaged or joined for multiplayer games. There are also achievements, communities, and user biographies within this system, making it roughly equivalent to a console delivery platforms such as Xbox Live.