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.
Variations that create colored stamps with interesting designs. They are all blur variations (they ignore their inputs) and by default use true color (they set specific red, green, and blue values) though there is an option to use the gradient (direct color).
Variations that generate specific shapes using polar coordinates. Unlike normal blurs, which ignore the input point, these variations are half blurs that take the angle of the input point (theta) and compute a random distance (rho) within the shape. This allows some flexibility in coloring. They can be substituted for normal blurs in many flames; if it doesn’t work, try adding some pre_blur to the transform to generate random angles (this is done for the examples here).