The ground beneath your feet is a wonderful thing, but it makes a poor bed. To get proper rest, you need a sleeping pad. These pads perform two separate purposes: insulating and cushioning.
Cushioning is nice, but insulation is often vital. The three major types of sleeping pads offer those two traits in different measures.
Air Pads
Air pads are like slim air mattresses. They're comfortable, don't weigh much, and are easy to pack. You can also control their firmness.
On the negative side, an errant stick could turn your air pad into an empty pad. Additionally, their firmness can shift with the temperature.
If you fill one up with your breath, moisture inside the pad could breed mold. However, hand pumps reduce that possibility.
Foam Pads
Foam pads are composed of foam with small air cells. They're less expensive than other options, so they're perfect for budget-conscious campers.
These pads are lightweight, and you can roll them up for transport. Punctures aren't a concern with foam pads, and they offer decent insulation.
Because they're firm and thin, they're not very comfortable, however. Many people like using them under other sleeping pads. If you throw a foam pad under your air pad, you'll get a perfect combination of comfort and insulation.
Self-Inflating Pads
Self-inflating pads have traits of both air pads and foam pads. When you open a self-inflating pad's valve, its interior foam expands. This option is comfortable, well-insulated, and easy to use.
There are some drawbacks, though. Self-inflating pads take up more packing space, and they're not puncture-proof.
No matter what type of pad you choose, check its R-value before purchasing. Higher R-values mean more insulation.