How Computers Work

CPU, RAM vs storage, files, processes, threads, and what the operating system actually does — the ground every other tutorial stands on.

Every tutorial on this site — Docker, NestJS, Keycloak, payments — quietly assumes you already know what a process is, why RAM matters, and what the operating system is doing underneath your code. This series is where that knowledge comes from.

It starts from "what is a computer, really?" and builds up, one layer at a time: how data is stored as numbers, how the CPU runs instructions, why RAM and storage are different things, how files and folders work, what the operating system does, and how processes and threads let many programs run at once. The final chapter traces a single click — opening an app — all the way from your finger to pixels on the screen, using everything from the chapters before it.

There's no code to write and nothing to install. The hands-on parts use tools already on your computer: Task Manager on Windows, Activity Monitor on macOS, and System Monitor or top on Linux.

When you finish, the natural next step is Command Line Basics, which puts files, paths, and processes to work from the terminal.

  1. 01What Is a Computer, Really?Input, processing, storage, and output — hardware vs. software, and the layers every program sits on top of.
  2. 02Bits, Bytes, and Everything Is a NumberWhy computers store everything as 0s and 1s, how text, images, and sound become numbers, and what KB, MB, and GB really mean.
  3. 03The CPUWhat the processor actually does, the fetch–decode–execute cycle, clock speed and cores, and how the code you write becomes machine code.
  4. 04Memory: RAM vs. StorageRegisters, cache, RAM, SSD, and hard drives — why computers need several kinds of memory, how much faster each one is, and what happens when RAM runs out.
  5. 05Files and File SystemsWhat a file really is, how folders and paths work, what file extensions do and don't mean, hidden files, and a first look at permissions.
  6. 06The Operating SystemWhat the operating system actually does — the kernel, drivers, system calls, user vs. kernel mode, and what happens when you turn the computer on.
  7. 07ProcessesA program vs. a process, process IDs, why every process gets its own memory, how the OS shares one CPU between hundreds of them, and how processes end.
  8. 08Threads and ConcurrencyThreads vs. processes, concurrency vs. parallelism, why apps freeze, and a first look at race conditions — the bug that only appears sometimes.
  9. 09Input/Output: Talking to the WorldWhat counts as I/O, why it's so slow compared with the CPU, how interrupts work, blocking vs. non-blocking I/O, and why async code and the event loop exist.
  10. 10Putting It All TogetherTrace a single action — opening an app and loading a web page — from the click to pixels on the screen, using everything from the series. Plus a recap and what to learn next.