A round brush is a type of hair styling tool that features a cylindrical shape with bristles arranged around it. It is commonly used to create volume, curls, or waves in hair. When blow-drying, the round brush helps to lift the hair at the roots, giving it a bouncy and full appearance. These brushes come in various sizes, allowing users to achieve different styles. A smaller round brush is great for tighter curls, while a larger one is ideal for loose waves. Many people use a round brush in combination with a hair dryer to enhance their styling results.