"Beware of the unknown" is pretty good advice for dark woods and creepy houses. But when you are trying to pimp out your Galaxy S3, you're going to want to delve deep into the unknown. While the Play Store has a ton of great apps, many softModders want to customize their phones with third party apps that are blocked by default.
In order to install apps from places other than the Play Store, you'll need to enable Unknown Sources.
To do that, go to Settings -> Security -> Device Administration and make sure Unknown Sources is checked.
It's as simple as that. Now you can enjoy a plethora of apps that any softModder couldn't do without. Check out just some of the great apps we found in the unknown.