A roller bearing is a type of bearing that uses cylindrical rollers to reduce friction between moving parts. These rollers are placed between two rings, known as the inner and outer races, allowing for smooth rotation. Roller bearings are commonly used in various applications, including automobiles, industrial machinery, and electric motors, due to their ability to support heavy loads and withstand high speeds. The design of roller bearings helps distribute weight evenly, which enhances their durability and performance. They come in different types, such as cylindrical, spherical, and tapered roller bearings, each suited for specific applications and load conditions.