http://www.theverge.com/2014/3/1/5460556/steams-family-sharing-open-to-all [quote]Last September Valve launched a small beta for Steam's new family sharing feature, and today it's finally available for everyone. The service lets Steam users share their entire game library with friends and family on up to 10 authorized devices. If you see a friend or family member playing a game you want to check out, you can send them a message requesting authorization. Game saves and achievements will remain separate, however, and the service doesn't work for every one of Steam's games — titles that require a subscription fee or third-party key, for instance, aren't accessible through family sharing. Your account can also only be accessed by one user at a time, so any time you're sharing a game, you won't be able to access it yourself. The feature is available now.[/quote] This is what Microsoft was going to do with the Xbox One but well, they didn't. Only 1 person can be playing a game from your Steam account at any one time, so that's a bummer, but it's still a great way for your friends to play some of your games every once in a while.