Which tool is primarily used for tightening bolts?

A wrench is specifically designed to tighten or loosen bolts and nuts, making it the ideal tool for this task. It typically features an adjustable jaw or fixed opening that grips onto the bolt heads, allowing for precise torque application. This capability is crucial since proper tightening is necessary to ensure that the bolts remain secure and perform effectively in mechanical assemblies.

In contrast, a screwdriver is intended for screws, a hammer is used for driving nails and other similar tasks, and pliers are versatile tools that can grip, twist, and cut materials but are not primarily designed for the specific task of tightening bolts. The efficiency and design of a wrench make it the preferred choice for working with bolts, ensuring that the connection is both strong and safe.