A reamer is a specialized tool used in machining to enlarge and finish holes with precision. It helps create a smooth, accurate surface inside a hole, ensuring that it meets specific size and shape requirements. Reamers come in various types, including hand reamers and machine reamers, each designed for different applications and materials. These tools are often made from high-speed steel or carbide, which allows them to cut through tough materials effectively. Reamers are commonly used in industries like automotive, aerospace, and construction, where precise hole dimensions are crucial for the assembly of parts and components.