The term finish is often used loosely to refer to any chemical that is applied to wood. The term actually refers to a clear protective coating that sits on or in the surface of the wood. Stain, Paint, and Finish are the three primary classifications for common wood treatments. Stains contain pigments and are used to tint the wood. Paints contain colored pigments and sit on the wood to form a protective coating.
Some finishes are simply paint with out the pigment that lay down a clear protective coating.
There are five common types of finishes on the market. Many professionals will use a spray gun for smooth even coats. When you are selecting a clear finish it is important to remember the qualities you require from the finish. It must protect the wood. It must be durable enough for the intended application.