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.

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Waves

Variations that add waves to x, y, and/or z. There are a lot of different variants on this theme, differing in the parameters available and how they are applied.

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Blobs

These variations deform the plane by pinching it towards the origin, making a blob-like shape. The math is similar to that of rose curves, but these are standard variations, not blurs.