Every computer, server, phone and smart device runs on an operating system (OS) — the software layer that manages hardware and lets every other program run. Choosing the right OS, and knowing when it stops receiving security updates, is one of the most overlooked basics in IT.
This guide explains what an operating system actually does, the major families in use today, and — most importantly — their official start (release) dates and end-of-life (EOL) support dates, so you know exactly when a system needs to be upgraded. Use the tabs below to jump straight to what you need.
EOL dates are set and occasionally extended by vendors. The dates below reflect officially published lifecycle data as of this article's publish date. Always confirm the current date on the vendor's official lifecycle page before making upgrade decisions — see the "How to Check" tab below.
What is an Operating System?
An operating system is the software that manages a computer's hardware (CPU, memory, storage, network) and provides the platform on which applications run.
Without an OS, every application would need to talk directly to hardware — which is why operating systems exist: they standardize that interaction through drivers, schedulers, file systems and security models so app developers don't have to reinvent the wheel.
Types of Operating Systems
Desktop / Client OS
Built for personal computers and laptops: Windows, macOS, and desktop Linux distributions (Ubuntu, Fedora, Linux Mint).
Server OS
Optimized for running services without a graphical interface: Windows Server, Red Hat Enterprise Linux (RHEL), Ubuntu Server, Rocky Linux, Debian.
Mobile OS
Built for phones and tablets: Android and iOS, both with their own update and support cycles.
Embedded / Real-time OS
Run on dedicated hardware like routers, IoT devices and industrial controllers: examples include embedded Linux, FreeRTOS, and VxWorks.
Windows: Versions and EOL Dates
| Version | Release Date | End of Support (EOL) |
|---|---|---|
| Windows 10 | July 2015 | October 14, 2025 (ended) |
| Windows 11 | October 2021 | Rolling — each feature update supported ~24–36 months |
| Windows Server 2019 | October 2018 | January 9, 2029 (extended support) |
| Windows Server 2022 | August 2021 | October 14, 2031 (extended support) |
| Windows Server 2025 | 2024/2025 | ~2034 (extended support, projected) |
Windows 10's end of support means no more free security patches — a major reason organizations still running it should plan a Windows 11 migration or pay for Extended Security Updates (ESU).
Linux Distributions: Versions and EOL Dates
| Distribution | Release Date | Standard Support Ends | Extended (LTS/ESM) Ends |
|---|---|---|---|
| Ubuntu 20.04 LTS | April 2020 | April 2025 (ended) | April 2030 (ESM) |
| Ubuntu 22.04 LTS | April 2022 | April 2027 | April 2032 (ESM) |
| Ubuntu 24.04 LTS | April 2024 | April 2029 | April 2034 (ESM) |
| Debian 11 "Bullseye" | August 2021 | August 2024 (ended) | ~2026 (LTS) |
| Debian 12 "Bookworm" | June 2023 | ~2026 | ~2028 (LTS) |
| RHEL 8 | May 2019 | May 2024 (full support ended) | May 2029 (maintenance) |
| RHEL 9 | May 2022 | May 2027 | May 2032 (maintenance) |
| CentOS Linux 8 | September 2019 | December 31, 2021 (discontinued) | — |
| Rocky Linux 9 | July 2022 | May 2027 | May 2032 |
Note that CentOS Linux as a downstream RHEL rebuild was discontinued in favor of CentOS Stream, which is a rolling-release upstream development branch rather than a stable production OS — this is why many production servers migrated to Rocky Linux or AlmaLinux.
macOS: Versions and Support
| Version | Release Date | Security Update Support |
|---|---|---|
| macOS Ventura (13) | October 2022 | Ended with macOS 16 release cycle |
| macOS Sonoma (14) | September 2023 | ~3 years from release (typical Apple policy) |
| macOS Sequoia (15) | September 2024 | ~3 years from release |
Apple typically provides security updates for the current macOS release plus the two previous versions — roughly a 3-year window per version, though Apple does not publish exact end dates the way Microsoft and Linux vendors do.
Mobile Operating Systems
Android: Google guarantees major OS and security updates for around 3–7 years depending on the device manufacturer (Pixel and Samsung flagship devices now offer up to 7 years). Support varies significantly by phone brand and model.
iOS: Apple typically supports a device with the latest iOS version for around 5–6 years from release, with most recent iPhones still receiving the newest iOS update for several years after launch.
Why End-of-Life Dates Matter
Once an OS reaches end-of-life, the vendor stops releasing security patches. Any new vulnerability discovered after that point remains permanently unfixed unless you pay for extended support. This makes unsupported systems a top target for attackers, and a common compliance failure in audits (PCI-DSS, ISO 27001, SOC 2 all flag unsupported OS versions).
How to Check Support Dates Yourself
- Windows: Microsoft's official Lifecycle page (search "Microsoft Lifecycle [product name]")
- Ubuntu: Canonical's official release page (search "Ubuntu releases end of life")
- RHEL: Red Hat's official lifecycle page (search "Red Hat Enterprise Linux life cycle")
- Debian: Debian Wiki's LTS page (search "Debian LTS")
- macOS: Apple's security updates page lists which versions still receive patches
Bookmark these pages for any OS your organization runs in production — checking them once a year takes minutes and prevents running unsupported software unknowingly.
Frequently Asked Questions
Can I keep using an OS after its end-of-life date?
Technically yes — the OS keeps running — but it stops receiving security patches, making it increasingly risky over time. Extended Security Update (ESU) programs exist for some products (like Windows 10) at a cost.
What's the difference between "standard support" and "extended support"?
Standard support includes new features plus security and bug fixes. Extended support (or LTS/ESM in the Linux world) usually only includes critical security patches, with no new features.
Why do Linux LTS releases last longer than regular releases?
Long Term Support (LTS) releases are specifically built for production stability — vendors commit to years of patches instead of months, which is why most servers run LTS versions rather than the latest release.
Conclusion
Understanding operating system lifecycles isn't just trivia — it directly affects security, compliance and budget planning. Whether you manage one laptop or a fleet of servers, knowing each OS's release date and end-of-life date helps you plan upgrades before they become emergencies.
Make it a habit: audit your OS versions against official vendor lifecycle pages at least once a year.
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