Table of Contents Link to heading

What an Operating System Does
OS Selection Criteria
Microsoft Windows
Apple macOS
Linux
Linux Distribution Families

What an Operating System Does Link to heading

An operating system is the software layer between hardware and applications. Its three primary responsibilities are:

User interface: Accepting and executing commands or interactions from users
Application lifecycle management: Loading, scheduling, and terminating software processes
Hardware resource management: Abstracting CPU, memory, storage, and I/O devices for applications to use without needing direct hardware access

Of the three major OS families in widespread use today — Windows, macOS, and Linux — only Windows is built on a proprietary, non-Unix-derived codebase. macOS and Linux both trace their architecture to UNIX, which has practical implications for portability, tooling, and behaviour.

OS Selection Criteria Link to heading

Choosing an OS for a given role involves several intersecting factors:

Factor	Questions to Ask
Role	Single-user desktop, multi-user server, embedded device, container host?
Function	Does it need to run specific applications? What is the technical skill level of operators?
Life cycle	How long must this system be supported? Does the OS have an LTS release?
Stability	Is the distribution on a bleeding-edge or stable release cadence?
Compatibility	Must it run legacy software? Does it support backward-compatible APIs?
Cost	What are the total costs — licensing, support, training, tooling?

Microsoft Windows Link to heading

Windows is the dominant desktop OS and has significant server market share through Windows Server. Key characteristics:

Available in both desktop and server editions (Windows Server)
Long, predictable release cycles (typically 3–5 years for major versions) with extended maintenance support
Strong emphasis on backward compatibility — software written for older Windows versions often runs on newer ones
GUI-first design, though PowerShell has significantly improved scripting and automation capabilities
Closed-source; patches and security fixes depend entirely on Microsoft’s release schedule

For sysadmins, Windows environments typically mean Active Directory, Group Policy, IIS, and PowerShell — a distinct toolchain from Linux.

Apple macOS Link to heading

macOS is a UNIX-certified operating system that runs exclusively on Apple hardware:

Available in desktop and server configurations (macOS Server adds management and sharing packages)
More frequent major release cycles than Windows (typically 12–18 months)
UNIX certification means POSIX compliance — many Linux CLI skills transfer directly
Closed-source core, though many components (Darwin kernel, LLVM/Clang) are open source
No annual licensing fees for the OS, but Apple hardware carries a premium

macOS is common in development environments where engineers need both native Unix tooling and access to macOS-specific applications (Xcode, design software).

Linux Link to heading

Linux is unique in that selecting “Linux” requires a second decision: which distribution? The kernel is common across all; distributions differentiate on package management, default configuration, init system, release cadence, and support model.

Linux-specific decision criteria:

Factor	Linux Considerations
Role	Distributions exist for servers, desktops, embedded systems, security testing, scientific computing, and more
Function	Distribution selection can be scoped to specific workloads (e.g., RHEL for enterprise servers, Kali for penetration testing)
Life Cycle	LTS releases available on most major distributions (Ubuntu LTS: 5 years, RHEL/Rocky: 10 years, SUSE LTS: 13 years)
Stability	Stable, testing, and unstable branches available on distributions like Debian
Cost	Zero licensing cost for the OS; commercial support available from vendors like Red Hat, Canonical, and SUSE

Linux Distribution Families Link to heading

Red Hat Family Link to heading

Red Hat is the dominant Linux vendor in enterprise server environments:

Red Hat Enterprise Linux (RHEL): The commercial product — stable, long release cycles (10-year support), certified for enterprise workloads. Requires a subscription for support and official packages.
Fedora: Red Hat’s upstream community distribution, featuring the latest software. Fedora is where new features are tested before incorporation into RHEL.
Rocky Linux / AlmaLinux: Community-maintained, binary-compatible rebuilds of RHEL. The functional successors to CentOS after Red Hat changed its model.
Scientific Linux: A specific-use distribution based on Red Hat, targeted at scientific computing environments.

Red Hat distributions use RPM packages and the dnf/yum package manager.

SUSE Family Link to heading

SUSE is one of the oldest Linux distributions, with a strong presence in European enterprise environments:

SUSE Linux Enterprise (SLE): Commercial server product with up to 13 years of long-term support — the longest of any major distribution.
openSUSE Leap: A stable, community distribution that tracks SLE sources closely. Suitable for production use.
openSUSE Tumbleweed: A rolling-release variant for users who want current software.

SUSE distributions use RPM packages and the zypper package manager, with the YaST administration tool as a distinguishing feature.

Debian Family Link to heading

Debian is a community-maintained distribution that prioritises stability and open-source principles:

Debian: The upstream distribution with strict package stability requirements. Stable releases are used extensively for servers; the testing and unstable branches are used by developers.
Ubuntu: The most widely deployed Debian derivative. Available in desktop, server, and minimal cloud variants. Ubuntu’s LTS releases (every 2 years, supported for 5 years) are a common baseline for server deployments and cloud images.
Linux Mint: A desktop-focused derivative of Ubuntu, aimed at users transitioning from Windows.

Debian-family distributions use .deb packages and the apt package manager.

Android Link to heading

Android is a Linux-based OS developed by Google for mobile devices. While the kernel is Linux, Android replaces the GNU userland with Google’s own runtime (originally Dalvik, now ART) and application framework. It is not compatible with standard GNU/Linux packages and represents a distinct platform despite sharing the kernel.

Operating System Comparison: Windows, macOS, and Linux Distributions