Steam’s Family Library Sharing is now released for all Steam users. Players who share computers can now also share their available libraries with one another, each earning their own achievements and saving their own game progress to the Steam Cloud. It’s all enabled by authorizing shared computers and the familiar accounts that log into them. Source Valve
Steam Family Sharing has been in Beta since last year and is now fully available to all Steam users. Steam is a free digital online gaming service where you buy PC, also play Free to Play games and Demos. For more info on Steam Family sharing go here to the Steam Family Sharing Community page.