Summarize this article in one sentence.
Carpet pads don’t just make your carpets more comfortable to walk on, because they can also protect your carpet. When you place a heavy piece of furniture on the carpet, the pad will help absorb the weight, and help prevent dents from forming.  Carpet pads come in different thicknesses, and it’s important that you choose the right pad for the type of carpet you have. Typically, household carpeting pads should be between ¼ inch and 7/16 inch (6.3 and 11 mm) thick, and should have a density of about 6 pounds (2.7 kg) per cubic foot (30 cm). Furniture dents form because heavy furniture compresses the same fibers in the same way for too long. An easy way to stop this from happening is to move the furniture often so that it doesn’t sit on the fibers long enough to compress them. Move the furniture by about an inch (2.5 cm) every one to two months to stop dents from forming. This method works best with small furniture and furniture that’s on casters. Furniture cups and gliders are pads that you place under furniture feet. These spread out the weight of the furniture more evenly among more fibers. That way, the furniture isn't just compressing a few fibers, so dents don’t form.  Cups tend to slide under furniture feet, and don’t get attached to the actual feet. Gliders are also designed to help furniture slide without causing scrapes. They often have sticky backs that attach to the feet, or screws or pins that get inserted into the wood. Carpets with shorter pile (shorter fibers) are generally easier to maintain and clean, and they aren't as dent-prone as carpets with longer pile. When it comes time to re-carpet or change your rugs, look for shorter fibers as opposed to longer and shaggier ones.

Summary:
Use carpet pads. Move furniture regularly. Use cups or gliders. Choose carpeting with a shorter pile.