Section 1
Presets- Just as with any other tool, this offers you a variety of presets already made for the selected tool.Brush Selector- From here you can pick from a variety of brush tips to use. Some are plain shapes while others are more creative like leaves, etc. You can easily create your own brush to choose from as well.
Shape- This will make your brush tip either square or circular. ** Note on this feature: You might select a square brush tip and then adjust several of the settings in the options bar--such as Hardness or Opacity--that can affect the shape of the brush and make it appear more round. I will show you an example shortly.
Size- What the name implies, the size of the brush tip.
Hardness- Determines the solidity of the brush.
Section 2
Step- Determines the distance interval that elapses between applications of paint, with each application defined as a single, continuous brush stroke. Lower values produce a smoother, more continuous appearance; higher values create a choppier appearance.Density- The ability of an object to stop or absorb light. The less light reflected or transmitted by an object, the higher its density.
Thickness- Determines the width of the brush stroke. A setting of 100 produces a brush tip that is completely round or completely square, depending on the Shape setting. As the Thickness setting decreases, the brush becomes increasingly narrow.
Rotation- Applies rotation to a noncircular brush tip.