Add an overlay of random noise to an element.
Noise makes an element more visually busy, but in a subtle way. This is useful if you want it to feel more realistic, or less “perfect”. It also makes something more interesting to look at in general, without distracting from the element itself too much.
In the example below, the noise is applied only to the right side.
You probably don’t need the noise to be as noticeable as you might assume.