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 roller is dipped into a tray of paint, allowing it to absorb the liquid, and then rolled onto walls or ceilings to create a smooth finish. Paint rollers come in various sizes and textures, making them suitable for different types of paint and surfaces. They are often used in conjunction with a paint tray to hold the paint and a paintbrush for edges and corners. This combination helps achieve a professional-looking result in home improvement projects.