A CPU cooler is a device designed to dissipate heat generated by a central processing unit (CPU) during operation. It helps maintain optimal temperatures, ensuring the CPU functions efficiently and preventing overheating, which can lead to performance issues or hardware damage. There are two main types of CPU coolers: air coolers and liquid coolers. Air coolers use metal heatsinks and fans to draw heat away from the CPU, while liquid coolers circulate coolant through a closed loop to transfer heat away more effectively. Both types are essential for maintaining system stability and longevity.