To understand what a kernel is, you first need to know that today´s operating systems are built in layers. Each layer has different functions such as serial port access, disk access, memory management, and the user interface itself. The base layer, or the foundation of the operating system, is called the kernel. The kernel provides the most basic low-level services, such as the hardware-software interaction and memory management. The more efficient the kernel is, the more efficiently the operating system will run.