Final answer:
A box-end wrench is a type of wrench that completely surrounds the bolt head or nut to provide a tight grip.
Step-by-step explanation:
A wrench that completely surrounds the bolt head or nut is called a box-end wrench. It is designed to provide a tight grip on the fastener and prevent any slippage. The box-end wrench has a closed loop on one or both ends, allowing it to fully enclose the nut or bolt head.
For example, in Figure 2.31, we can see how a wrench provides grip and mechanical advantage in applying torque to turn a nut. When using a box-end wrench, you would turn it clockwise to tighten the nut and counterclockwise to loosen it.