The handle is typically made out of wood, but can also be made from plastic acrylic or other materials. Handles can be long or short depending on what you need from the brush. The Ferrule is what holds the bristles of the head in place, and the bristles make up the head and is the business end of the brush,2. Brush Shapes
These are the most common brush shapes available.
But they are by no means the only types. Brushes come in many different shapes, thickness's, density's and heights of the bristles. Different brands will be different on all of these points, even though the basic shape of the head is similar. So when you buy a #4 round for example, it will may not be the EXACT same thickness or height as another brand because each will vary on when the tapering of the bristles starts, or how long the bristles are. Good things to keep in mind when shopping for brushes.
1. Brush Fibers
Knowing more about the nature of different brush fibers will help you choose which brushes to get for what type of paint.
Natural Hair also behaves differently when wet.
Dry to wet A) Squirrel mop 2) Sable 3) Synthetic fibre
As you can see the natural hair brushes open up a lot more then the synthetic, allowing them to pick up and hold more paint.
It's also good to note that synthetic fiber brushes are the best for makeup, and face paint.
Comparison of all 3: