Typically, a kernel (or any comparable center of an operating system) includes an interrupt handler that handles all requests or completed I/O operations that compete for the kernel's services, a scheduler that determines which programs share the kernel's processing time in what order, and a supervisor that actually gives use of the computer to each process when it is scheduled. A kernel may also include a manager of the operating system's address spaces in memory or storage, sharing these among all components and other users of the kernel's services. A kernel's services are requested by other parts of the operating system or by application through a specified set of program interfaces sometimes known as system calls.

Because the code that makes up the kernel is needed continuously, it is usually loaded into computer storage in an area that is protected so that it will not be overlaid with other less frequently used parts of the operating system.