If you want to make sure that the electricity of your car is going where it needs to go then you have to have a battery cable and ground strap. The engine in your gas is powered by gasoline but most everything else in the car is powered by electricity which runs off the engine. Some cars actually use hydraulic fluid but most use a large battery that powers other parts of the car. An alternator continues to charge the battery and the alternator is powered by the engine. If your car is having trouble starting or the electrical parts are not getting the power that they need, it may be because of a bad cable and ground. It may be one thing to check before replacing the whole thing because it costs less to replace just the battery cable and strap. The cable and strap may fray and pull apart or become damaged by water and bent when someone was working under the hood. It is important to replace the part to ensure that the engine and all equipment on the car are operating properly. Always check a wiring diagram to see how many your car needs.
The battery cable and ground strap are bundles of copper wires encased in a rubber sleeve to prevent damages and shocks. They have one end that connects to the terminal on the battery and another end that connects to the body of the car to ground. They have always been used in automobiles and really have not changed much over the years because automotive batteries have not changed a lot. It is a functional part and is usually black or grey in color. The positive battery cable and ground strap may be red or may have a red attachment. It may be several inches long and may run around the different parts of the engine. It is probably less than a half inch thick.
Changing out the battery cable and ground strap on your car is a simple job that can be accomplished at home with the right tools. Here are some basic instructions, however they are not a replacement for consulting with a qualified mechanic. Make sure that the car has cooled down and is in a safe place where you have plenty of light.