Introduction and method - 1/6

What this is about#

Ask “which operating system dominates the market?” and the conversation almost always slides toward a single arena: Windows versus macOS on the desktop. That is a narrow view. The software that really runs the world mostly executes elsewhere — in the billions of connected devices (internet boxes, televisions, cars, surveillance cameras, industrial sensors…), in the billions of phones, in the servers that answer every web page, in game consoles, cash machines, and all the way up to supercomputers.

This series takes stock of that market, segment by segment, in 2026. The aim is not to defend a thesis but to look at the figures where they exist, with their sources, and to say honestly what they show — including when reality is more nuanced than it looks. One underlying finding nonetheless emerges: in 2026, across the great majority of segments, Windows is retreating or was never present, and the most widespread system is not just Linux, but the Unix family in the broad sense. This is not a final verdict — a market can turn around, a new player can emerge — but a snapshot at a given moment.

How to read these figures#

Before getting into the detail, a few methodological cautions. They matter: these figures measure very different things, and it is easy to make them say what they do not.

• StatCounter measures page views, not machines. Its figures come from a statistics tracker placed on websites: they reflect traffic, not the installed base. They can also have blind spots — in 2026, a large share of “unidentified” visits briefly distorted the desktop reading before being resolved (see the article on the breaches).
• W3Techs only sees the servers that expose their system. It scans the most-visited sites and reads the system only when the server announces it. But a growing share of the web sits behind CDNs and reverse proxies that hide the origin server: what is observed is the edge, not necessarily the machine that actually hosts the site.
• Units, value, installed base, and sales are not the same. A share “by value” (by revenue, the favourite metric of analyst-firm reports) is not a share “by units” (by number of devices): in smartphones, Apple is a minority by units but captures most of the sector’s value. Likewise, the installed base (machines in service) is not the year’s sales, and worldwide figures often differ from US figures. We point this out whenever it matters.
• Linux is not the only alternative to Windows. Many segments are held not by Linux but by BSD (such as FreeBSD) or by proprietary systems (QNX, VxWorks, the macOS kernel…). Writing “Linux” everywhere would be a mistake; we distinguish.

For each segment, we distinguish four situations — this is the key to reading the whole series:

• (a) Windows was present, then disappeared — either a genuine retreat from a significant position (the smartphone, the firewall, the car), or a failed foray: an attempt to enter that never took hold (the tablet, the watch, the VR headset, the NAS). In both cases the withdrawal can be dated, to an end of sales or of support.
• (b) Windows was never present — the market was already Unix’s, and Linux or BSD replaced Unix, not Windows.
• (c) Windows is still present — the strongholds, which must be named with the same honesty as the retreats.
• (d) Windows was not there and took a significant, even dominant share — a conquest. Rarer in today’s landscape, but real: the game console, some professional terminals, the workstations wrested from the Unix world.

These four situations are not mutually exclusive — today’s stronghold is often the fruit of yesterday’s conquest, so that (c) and (d) overlap; and an acquired position can crumble, opening a breach. They give the plan of the series: (a) is the subject of “Where Windows retreated or never broke through”, (b) of “Where Windows never reigned”, and (c) and (d) still firmly held of “The strongholds Windows still holds”. The segments where Windows’s position is receding today — the desktop, which is cracking, along with databases and game consoles, two conquests in reflux — are gathered in “The breaches: where Windows is receding”. A final article attempts a worldwide count and concludes.

What we mean by “Linux” and by the “Unix family”#

A word on vocabulary, because the ground is a minefield — and because this series reasons at the level of the kernel and its lineage, not the distribution. Three clarifications.

Even Windows is not a single system. In this series we distinguish two unrelated kernels: the NT kernel, modern and hybrid, which powers Windows 10/11, Windows Server, the Xbox, Windows Phone 8+ and the IoT/embedded editions; and Windows CE (Windows Embedded Compact), an entirely separate real-time kernel, which ran Pocket PC, Windows Mobile, Windows Phone 7 and countless industrial terminals — reaching end of life in 2023. When the distinction matters, we name the variant.

“Linux”: one kernel, dozens of userlands. The Linux kernel is one thing; the systems built on it are many, and they do not share the same userland — starting with the C library, the basic layer between programs and the kernel:

“Linux” therefore refers sometimes to the kernel (shared also by televisions, cars, internet boxes…), sometimes to GNU/Linux, the complete system built on glibc and GNU tools. Android, Alpine or OpenWrt run on the Linux kernel without being GNU/Linux: they use a different C library (Bionic, musl) and an entirely different userland. Conversely, you find real GNU/Linux where you’d least expect it: SteamOS, on Valve’s handheld console (a breach of the desktop, covered later), is Arch-based; and WSL2 embeds a full GNU/Linux distribution inside Windows, on a Linux kernel that Microsoft compiles and maintains itself. A sign of the times.

This table is illustrative, not exhaustive: most of the other systems in the series are likewise Linux with a bespoke userland — televisions (Tizen, webOS, Roku OS), NAS devices (Synology DSM, QNAP QTS), network equipment (Cisco, Arista), even firewalls sold as “proprietary” (FortiOS, PAN-OS): same Linux kernel, different stack.

And even within GNU/Linux, almost everything diverges: the init system (systemd, SysV, OpenRC, runit), the display server (X11 or Wayland), the desktop environment (GNOME, Plasma, Cosmic, XFCE…), the package manager. Two GNU/Linux systems may share, on the userland side, nothing but glibc.

What holds them together: the kernel and its ABI. Despite all this, they share the same Linux kernel and — above all — its stable interface to userland, the ABI (Application Binary Interface): essentially, the set of system calls. This is Torvalds’s famous rule, “we do not break userspace”: the kernel must never break this interface, so that a binary that ran yesterday still runs tomorrow. It is precisely this stability that lets a full GNU/Linux stack (glibc, apt…) run on an Android phone, via a tool like proot, without recompiling anything — same kernel, same system calls. (Not to be confused with the C library’s ABI: glibc, musl and Bionic are not interchangeable with one another.)

The “Unix family,” one step higher. Grouping Linux, the BSDs and Darwin into a single “family” climbs another rung: this time, the kernels differ. FreeBSD, OpenBSD and NetBSD are complete systems, each from a single tree; the Darwin of macOS and iOS blends a Mach microkernel and a BSD layer; QNX (automotive, real-time) is a proprietary microkernel. This same heritage also covers the proprietary Unix systems of old — Solaris, AIX, HP-UX, IRIX — the very ones that Linux and the BSDs supplanted. What unites them is not a shared kernel, but a shared heritage: the POSIX model — the same notions of processes, files and descriptors, the same lineage from C and the Unix of the 1970s. It is at this level that one can say “the Unix family won”: a phone’s Android (Linux kernel), the PlayStation (FreeBSD) and the iPhone (Darwin) share no kernel, but they do share that heritage.

In short, in this series: “Linux” means the kernel and its lineage, unless GNU/Linux (the complete system) is explicitly stated; “Unix family” is the umbrella over all of it; and Windows (NT or CE) is the outsider that belongs to neither — but not the only one: a handful of purely proprietary systems belong to none of these families, from the real-time systems of avionics (VxWorks, INTEGRITY-178, PikeOS) to the mainframe z/OS, by way of VMware’s VMkernel and the consoles’ in-house microkernels.

Overview#

The table below summarises the segments covered in this series, with the share of the dominant OS and that of Windows. The detail, the sources, and the methodological caveats are in the corresponding articles.

A warning about this table: the bases of calculation differ from row to row, and the dates span 2024 to 2026. Depending on the segment, the same percentage may measure very different things:

• page views (web traffic, not machines) — smartphones (~69%) and the desktop computer (~71%), per StatCounter;
• websites (a count of sites) — web servers (~92% Unix), per W3Techs;
• shipments for the year or quarter (devices sold) — tablets, VR headsets, tills (POS), per IDC or Counterpoint;
• an installed base (machines actually in service) — cash machines;
• a count of systems or of compute cores (a direct tally) — the 500 of the TOP500 for supercomputers, the share of Azure cores for the cloud.

The percentages are therefore not comparable across segments and do not add up. The source of each figure is given in the articles that follow, where each segment is detailed. And where no reliable per-operating-system figure exists (CDNs, network equipment, mainframes…), the table says so — “no measured share”.