The Brush tool is one of the most versatile
tools in Photoshop. You can use it to paint
on any layer, just like a real paintbrush. And
you have different settings to choose from,
so you can customize it for different
situations.
For example, if you’re painting on a
transparent layer, you can choose the
Opacity setting to control how opaque the
brush strokes are.
Or if you’re painting on a textured layer,
you can choose the Texture setting to add
texture to the brush strokes. So whatever
you need to do, the Brush tool can help you
get it done.