A wrench or spanner is a tool used to provide a mechanical advantage in applying torque to turn bolts, nuts or other items designed to interface with a wrench.

In American English, wrench is the standard term, while spanner refers to a specialized wrench with a series of pins or tabs around the circumference. (These pins or tabs fit into the holes or notches cut into the object to be turned.) The most common shapes are called open-end wrench and box-end wrench.

In British English, spanner is the standard term. The most common shapes are called open-ended spanner and ring spanner. The term wrench refers to a type of adjustable spanner.^[1]

Higher quality wrenches are typically made from chromium-vanadium alloy tool steels and are often drop-forged. They are frequently chrome-plated to resist corrosion.

Hinged tools, such as pliers or tongs, are not generally considered wrenches.