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.

Posts tagged as disc

Disc Ngon

Based on a DeviantArt tutorial, great images from this Disc Ngon combo, great for tweaking.

Disc Julian Spherical

Electric sheep flame 244-52441 gave me the idea for this. As is customary, there is a lot of randomness.