A cooler pad is a hardware accessory placed beneath a laptop that reduces the laptops overall heat by dissipating the heat using fans. Cooler pads can also help with keeping your lap cool if working on a laptop while it's on your legs. The picture shows a picture of the Belkin laptop cooling pad, which connects to your USB port to power a small fan that helps keep a good airflow beneath the laptop.
Does my laptop need a cooler pad?
Every laptop should be designed to work without a cooler pad on any flat surface and it is not abnormal for a laptop to feel hot on the bottom. If you are using a laptop on your lap or any other non-flat surface or the laptop is overheating or rebooting it would be a good idea to purchase a cooler pad.