Brushes are very useful in graphic design, for applying effects, layer masks, textures, patterns and more.
While in their simplest form, brushes simply paint colors onto a canvas, in Photoshop, brushes can have all sorts of textures, effects and controls to achieve nearly any effect imaginable. Most designers have a few favorite brushes they go to, and some have a whole arsenal to choose from.
There are tons of great free brushes to download and use, and here’s some examples:
Ornamental Corners Brush
HUD Brush Pack
Paint Splats Brush
Paint Trails Brush
2D Tech Brush Set
Smoke Brush Set