Operating Systems
Windows, macOS, and Linux - what they're really doing under the hood, from first login to power user.
Watch it animated → Interactive, click-through walkthroughs for Operating Systems concepts.Basic
What an Operating System Actually Is The operating system is the manager sitting between your programs and the hardware; understand the kernel, processes, memory, and files and your whole computer stops being a mystery box.
The Filesystem, Explained A filesystem is the tree of files and folders the OS lays over raw numbered storage; a path is an address into that tree, permissions decide who may touch each file, and a few simple rules explain almost every 'file not found' or 'permission denied' you'll ever hit.
The Terminal & Shell, Explained What the black window actually is, the difference between the terminal and the shell, the everyday commands worth knowing, and the real power features - pipes, redirection, wildcards, and PATH - that make typing beat clicking.
Linux From Zero - For People Who've Never Used It and Are a Little Scared What Linux actually is, how to find your way around its filesystem and install software, how users and permissions work, and how to start and read background services - for someone who's never touched it.
Editing in the Terminal vim and nano survival: open, edit, save, and (the part everyone fears) quit, without losing your work or your SSH session.
How Your Computer Boots What actually happens between pressing the power button and reaching a login screen - firmware, bootloader, and kernel handing off control in sequence.
Intermediate
Processes, Memory & the CPU - Diagnosing a Slow or Stuck Machine What '100% CPU' and 'out of memory' actually mean, and how to find the one process that's the culprit - using top and Task Manager you already have.
Windows for People Who Use It Every Day What's actually underneath Windows - the NT kernel, drive letters and the real folder layout, services and the registry, and PowerShell - explained for someone who's used Windows for years but was never shown the manual.
macOS Under the Hood macOS is a polished Unix machine - Darwin and the XNU kernel underneath, a real Unix filesystem hiding beneath the Finder, apps that are secretly folders, and a Terminal that feels like Linux because it nearly is.
Deadlocks Explained What a deadlock actually is, the four conditions that must all be true for one to happen, and how to prevent and detect them in real code.
System Calls Explained The controlled doorway between your program and the kernel - why it exists, what happens during one, and why it matters for real performance.
Advanced
Linux for Servers The leap from desktop Linux to running a real server: a headless box you reach over SSH, services managed by systemd, logs read with journalctl, and a small discipline of users, cron, firewall, and updates that keeps it safe.