A collet chuck is a type of tool holder used in machining to securely grip a rotating tool or workpiece. It consists of a cylindrical sleeve, known as a collet, which can expand or contract to hold various sizes of tools. This design allows for quick changes and precise clamping, making it popular in applications like milling and drilling. Collet chucks are commonly used in conjunction with machines such as lathes and CNC (Computer Numerical Control) equipment. They provide better accuracy and repeatability compared to other clamping methods, ensuring that tools remain stable during operation, which is crucial for achieving high-quality results.