A wrench is a hand tool used for gripping and turning nuts, bolts or other fasteners to loosen, tighten or adjust them. There are many different types of wrenches, including crescent, pipe, channel, open-end, box-end, combination, and adjustable wrenches, each designed for a specific purpose. Wrenches come in various sizes and can be made from different materials such as steel, chrome vanadium or carbon steel.