When I first heard about Steam Family Sharing, I - like any rational, functional adult human - assumed it involved temporarily swapping families with another Steam user. Imagine my surprise (and, let's face it, horror) when it turned out that I'd be able to share my game library with other human beings. Disgusting! Unnatural! An abomination! Steam libraries are sacred property, and also I really don't want people trying to comprehend why I own Petz Dogz 2, Secret of the Magic Crystal, and the entire Postal series. Down that path lies only madness. But here we are. Steam Family Sharing is a thing, and it's now available to all Steam users.
If you need a quick refresher on how it all works, here's the Steam Family Sharing page. The long and short of it?
"Steam Family Library Sharing allows family members and their guests to play one another's games while earning their own Steam achievements and saving their own game progress to the Steam Cloud. It's all enabled by authorizing shared computers and users."
You can authorize up to five other organisms to sift through your library and learn all of your secrets. They must be online to play your games, but if you drop in and start playing the same game, they'll get booted after a brief period of time. This means that Valve has automated the process of being passive-aggressive to your family! What revolutionary advance will they think of next?
Of course, that means no multiplayer if only one of you owns a game, which is unfortunate. Also, it's rather inconvenient to set up if you're not in the same location as the person you're sharing with. You can't share unless both accounts in question have logged into in a specific machine. The obvious intent, then, really is for this feature to be kept in the family. It's still a pretty admirable feature overall, though. I mean, we're talking about the ability to play entire games for (functionally) free. So thanks, Valve. Thalve.