Pliers Video
Adjustable pliers are the basic type in most everyone's toolbox. They have two positions for the jaws and have teeth on the jaws to grab and hold items. One disadvantage is if your grip slips when holding a nut, the corners could get rounded.
Linesman pliers have a special cutter at the base of the jaws. These are used by electricians to cut through wire or electrical cable.
Channel lock pliers can adjust their jaws in several positions to extend the capacity of what they can hold. The jaws also have teeth to grip that workpiece.
Needle nose pliers have a very long thin jaws. These are great for bending a piece of wire around a screw. Most also have a built-in wire cutter.
Your toolbox must have a selection of these pliers to be complete.