A paint roller is a tool used for applying paint to large surfaces quickly and evenly. It consists of a cylindrical foam or fabric cover attached to a handle. The cover absorbs paint and allows for smooth application on walls, ceilings, and other flat areas. Using a paint roller can save time compared to traditional brushes, especially for big projects. It is often used in conjunction with a paint tray, which holds the paint and allows for easy loading of the roller. Paint rollers come in various sizes and textures to suit different types of paint and surfaces, making them versatile for home improvement tasks.