Think of tags as like a book index where you find words and which pages they are on, the same principle applies here. Although it's taken a stage further so it might not be the word, but the subject, so for example if you're looking for things to do with fractal gradients for example. A tag may bring back posts with gradient files, as well as posts that discuss gradients, or tutorials about them.
Our Facebook group has been running for some time now, and we have an amazing collection of members with all kinds of interests and specialties. Aside from sharing our art daily, we also have tutorials, resources, tons of flames and a great sense of community.