A CPU cooler is a device designed to dissipate heat generated by a central processing unit (CPU) in a computer. It helps maintain optimal operating 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 heat sinks 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.