An open-end wrench is a hand tool used for gripping and turning nuts and bolts. It features two parallel jaws at one end, allowing it to fit over fasteners of various sizes. The design enables quick adjustments and easy access to tight spaces, making it a popular choice in both professional and DIY settings. Open-end wrenches come in various sizes, often measured in either metric or imperial units. They are typically made from durable materials like steel to withstand high torque. Many tool sets include a range of open-end wrenches to accommodate different fastener sizes.