Drywall can be finished in a wide variety of textures, including smooth, skip trowel, swirl, orange peel, knock-down and popcorn. Each choice has advantages and disadvantages, including cost of application, how easy it is to paint and how well it hides flaws, but the choice is mostly aesthetic.
Some textures, such as orange peel and popcorn, are sprayed on with compressed air and an applicator gun. Other finishes are applied with a hand trowel, a knife, a brush or a roller. Hand-applied styles are generally more expensive due to the amount of labor involved. A smooth finish requires applying drywall mud with a roller, then smoothing the entire surface with the edge of a broad knife.