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What Is a Kernel? Overview & Definition

In the realm of technology, certain terms might seem intimidating or ambiguous to those not steeped in the field. One such term is “kernel“. This article aims to demystify this concept and clarify its relevance in computing.

What is a kernel?

A kernel, in the context of computing, is essentially the core of an operating system. It is the fundamental layer that exists between the computer hardware and the software. 

The kernel is responsible for interacting with hardware, and it is often considered the nucleus of a computer’s operating system.

What is the purpose of a kernel?

The kernel has a crucial role in the functioning of an operating system. It manages the system resources, including the processor, memory, and device drivers. It also handles system calls from software applications, allowing them to interact with the hardware. It is essential in controlling processes, managing memory, handling interrupts, and facilitating input/output (I/O) operations.

Where is the kernel?

The kernel is stored in the computer’s memory and is loaded into memory when the system boots up. It remains in memory until the system is shut down.

Being at the kernel level means having the highest level of access to system resources; hence, kernel-level programming requires a deep understanding of how the operating system and hardware function together.

Types of kernels

Monolithic kernels

Monolithic Kernels are a type of kernel where all operating system services operate in kernel space. This means the entire operating system, including schedulers, file system, and device drivers, is included in the kernel, making it large and complex. While this design can lead to efficiency due to the direct use of hardware and system resources, it can also result in system instability if a single service fails.


Microkernels, in contrast, operate by running the minimal amount of services needed for the operating system to function in kernel space. Most services, like device drivers or file systems, run in user space. This design can improve reliability and security, as a failure in one service won’t affect others. However, the increased communication between user space and kernel space can potentially lead to slower system performance.

Hybrid kernels

Hybrid kernels are an attempt to combine the best elements of both monolithic and microkernel designs. They aim to achieve the efficiency of monolithic kernels by running some services in kernel space while maintaining the reliability and security of microkernels by running other services in user space. However, the distinction between what runs in kernel space and user space is not as rigid as in microkernels, offering greater flexibility in design.

The role of kernels in computing

Understanding the concept of a kernel can enrich one’s knowledge of how computers work and the steps necessary to secure them. Because the kernel plays such an important role in a device, IT professionals have multiple ways to secure it, such as enabling kernel-mode hardware-enforced stack protection. Whether it is the Linux kernel or another type, the kernel is undeniably a fundamental part of an operating system. It plays a vital role in connecting software and hardware, making it possible for us to interact with technology in the seamless ways we do.

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