Off-roading requires you protect the undercarriage of your vehicle against rocks and other debris that can damage vital mechanical parts - leaving you stranded. Installation of the right skid plate protects your vehicle from such an event.
If you don't already have a skid plate & plan on some 4-wheeling, you should definitely add one. If, over time, your skid plate has become worn or damaged, you should replace it for full protection.
Find a selection of skid plates for many different applications listed here.