Interested in checking out a game on Steam but want to try before you buy? Now a friend can share it with you.
In fact, you won’t even need to buy it at all, since you can play your friend’s game as much as you want while logged into your own Steam account. Steam Family Sharing enables account holders to share their game libraries with up to five relatives and guests on up to 10 devices. First, the person sharing must authorize their guest. Then they can share their library in its entirety (it’s all or nothing) with that person.
Only one account can play a game at a time, eliminating the possibility that you could use the feature for multiplayer. If you want to play Portal 2 co-op with your brother, you’ll each still need your own copy. Previously, the only way to play games that you didn’t purchase with your own account was to play in offline mode.
Consoles like the Xbox 360 and the PlayStation 3 have permitted multiple users to share games on a local system for years, so in that way, Steam is playing catch up. On the other hand, Family Sharing shares games remotely, regardless of location, as long as they’re being played on one of the 10 authorized systems. This feature makes Steam more sharing-friendly than the previously mentioned consoles as well as the newer PlayStation 4 and Xbox One.
The Xbox One was actually planned to have a very similar family sharing method for its digital games. It was scrapped because it was tied to terribly unpopular digital rights management (DRM) plans.
Here is the official announcement from Valve with a FAQ that has more specific information.