A wrench is a hand tool designed to provide grip and mechanical advantage in applying torque to turn objects like nuts and bolts. It typically consists of a handle and a head with a shaped opening that fits onto the object being turned. The most common types of wrenches include open-end wrenches, box-end wrenches, adjustable wrenches, socket wrenches, and combination wrenches. Wrenches come in different sizes and shapes to fit a variety of bolts and nuts. They are commonly used in automotive and mechanical applications, plumbing, and construction.