Painting is a technique where a device sprays a coating (paint, ink, varnish, etc.) through the air onto a surface. Airbrushes are hand-held and used, instead of a brush, for detailed work such as photo retouching, painting nails or fine art. Air gun spraying uses equipment that is generally larger.
It is typically used for covering large surfaces with an even coating of liquid. Spray guns can be either automated or hand-held and have interchangeable heads to allow for different spray patterns.