What is kernel?

The kernel is the core part of an operating system. It sits between the computer’s hardware (CPU, memory, disks, etc.) and the software you run (applications, games, browsers). Its job is to manage resources, control hardware, and provide a set of basic services that programs can use.

Let's break it down

  • Process management: Starts, stops, and schedules programs so they can share the CPU.
  • Memory management: Keeps track of what RAM is free or used and protects each program’s data.
  • Device drivers: Talks to hardware like keyboards, printers, and graphics cards.
  • File system handling: Organises how data is stored and retrieved on disks.
  • System calls: Simple commands that programs ask the kernel to do (e.g., “open this file” or “send data over the network”).

Why does it matter?

Without a kernel, your computer would be a collection of raw parts that can’t work together. The kernel makes sure programs run safely, efficiently, and without interfering with each other. It also provides security by isolating apps and protecting the system from crashes.

Where is it used?

Every modern operating system has a kernel: Windows, macOS, Linux, Android, iOS, and even tiny systems like routers, smart watches, and IoT devices. Each of these uses a kernel to control the hardware and run applications.

Good things about it

  • Stability: Centralised control reduces random hardware conflicts.
  • Abstraction: Programmers don’t need to know the details of every device; they use simple system calls.
  • Multitasking: Multiple programs can run at the same time smoothly.
  • Security: Isolation and permission checks keep malicious code in check.
  • Portability: A well‑designed kernel can be adapted to many different hardware platforms.

Not-so-good things

  • Complexity: Writing a kernel is hard; bugs can crash the whole system.
  • Size: Monolithic kernels can become large, using more memory and storage.
  • Performance overhead: Switching between user programs and the kernel adds a small delay.
  • Update risk: Changing the kernel can break compatibility with drivers or applications.
  • Limited flexibility: Some kernels are not easily customizable for very specialised hardware.