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.

rosecurve group variation rhodonea

Rosecurve

The rose or rhodonea curve is shaped like a flower with petals, obtained by plotting a sine curve in polar coordinates. Its shape is determined by the frequency of the sine wave, denoted k.