Operating Systems

The software that turns hardware into a usable computer. How it shares the processor and memory among programs, how it stores files and protects them — and how technicians install, manage, back up and repair it.

18 pages 123 glossary terms A+

How to use this topic

The first pages explain what happens inside every operating system: the kernel, processes and threads, scheduling and memory. Then the topic turns practical — file systems and disks, users and permissions, installing an operating system — followed by pages for Windows, macOS, Linux and mobile systems, and the everyday work of updates, backups, remote access and troubleshooting.

Linux gets one overview page here; its command line and administration have their own topic, Linux & Command Line. PowerShell and Bash scripting continue in Bash & PowerShell Scripting. Virtualization is covered in Cloud, and antivirus and firewalls in Security.

Pages marked A+ cover material from the CompTIA A+ Core 2 exam.

Learning path

  1. 01What Is an Operating System?What an operating system does, how the kernel and the rest of the system divide the work, and the kinds of operating systems you will meet.BeginnerA+
  2. 02Kernel, System Calls and DriversHow the kernel protects the machine: user mode and kernel mode, system calls, interrupts, kernel designs and where drivers fit in.Intermediate
  3. 03Processes and ThreadsWhat a running program looks like to the operating system: processes and threads, their states, context switches, services and how to inspect or stop them.Intermediate
  4. 04CPU SchedulingHow the operating system shares a few CPU cores among many processes: preemption, time slices, round robin, priorities, and why a system feels slow.Intermediate
  5. 05Memory ManagementHow the operating system gives every process its own address space: virtual memory, paging, page faults, and swapping to disk.Advanced
  6. 06File SystemsHow an operating system organizes data on a disk: files and folders, NTFS, FAT32, exFAT, ext4 and APFS, journaling, and which to use where.BeginnerA+
  7. 07Disks, Partitions and VolumesPreparing storage for use: partitioning, formatting, mounting and drive letters, with Disk Management, diskpart and their Linux and macOS counterparts.IntermediateA+
  8. 08Users, Permissions and Access ControlWho may do what on a computer: user and administrator accounts, groups, User Account Control, NTFS and share permissions, and Linux file permissions.IntermediateA+
  9. 09Installing and Upgrading an OSGetting an operating system onto a computer: requirements, clean installs versus upgrades, boot media, images, unattended installs, licensing and activation.IntermediateA+
  10. 10Windows EssentialsFinding your way around Windows as a technician: editions, Settings and Control Panel, Task Manager, Event Viewer, the Microsoft Management Console, the registry and Group Policy.BeginnerA+
  11. 11Windows Command Line and PowerShellThe commands every Windows technician should know, in Command Prompt and PowerShell, and how PowerShell's cmdlets and pipeline work.IntermediateA+
  12. 12macOS EssentialsmacOS for technicians: the Finder, System Settings, Spotlight, Keychain, Time Machine, FileVault, installing apps and the Terminal.BeginnerA+
  13. 13Linux at a GlanceWhat Linux is and where you meet it: distributions, desktops and servers, package managers, the file system layout, and the first commands.BeginnerA+
  14. 14Mobile Operating SystemsAndroid and iOS compared: app stores and permissions, updates, synchronization, and how organizations manage phones and tablets.BeginnerA+
  15. 15Updates, Patches and DriversKeeping an operating system current: kinds of updates, patch management in organizations, drivers, rolling back, and why delay is risky.IntermediateA+
  16. 16Backup and RecoveryProtecting data and systems: full, incremental and differential backups, the 3-2-1 rule, restore points, recovery environments and testing restores.IntermediateA+
  17. 17Remote Access and ManagementWorking on computers you cannot touch: Remote Desktop, SSH, remote support tools, remote monitoring, and doing it securely.IntermediateA+
  18. 18OS TroubleshootingSolving common operating system problems: blue screens, boot failures, slow systems, crashing apps, and the tools to diagnose and repair them.IntermediateA+

Operating Systems glossary

Short definitions of the terms used in this topic. The full glossary covers every topic.