Previously, if you added a new friend or clicked attend to an event; it would automatically pop up on your wall letting everyone know who you just met or what you’ll be up to. If you wanted to hide it from the world, you would have to manually remove it from your wall yourself.
With Facebook’s new “Hide all activity…” button, you can selectively choose what sort of updates will be published to your wall and newsfeed. You can now pretty much be a ghost on the social network and your friends/stalkers won’t be able to keep tabs on you anymore. I guess it’s a good way to find out who’s really paying attention to you in the offline world.
Now you can break up or get into a relationship quietly without everyone asking you “really??!”