There are several brushes that can be divided in 2 categories;
Among other things they are mostly made of horsehair and pig hair. The small ones are mainly used to paint paintings.
Mostly made of nylon. These are known as powder puffs, for waxing and for paint based on water like latex etc.
When cleaning your computer, it is important that you know what you are going to clean, so you don't use the wrong brush...!