Microsoft is celebrating a big milestone for the latest iteration of its world-conquering operating system.
Windows 10 is now installed on over 400m systems worldwide. It has hit this number in 14 months. That's a fair bit quicker than Windows 7, which took over 20 months to reach the same goal. Windows 8 never got anywhere near that total.
After its release Windows 10 passed 75m installs in its first month, and 200m in six months. 1bn by 2018 had been the goal, although Microsoft has since said it will fall short of this.
Windows 10's rollout has been quite different to its predecessors, primarily because it was offered to free to existing Windows 7 and 8 users. Note also that the number includes tablets and mobiles that are running the latest OS version.
There's also the issue of alleged forced upgrades for PC users. Microsoft has denied this, but certainly there are plenty of folk who turned on their computer to suddenly find it packing the new OS, much to their surprise.