Microsoft has revealed that Windows 10 has been installed on 75 million machines since launch.

Yusuf Mehdi, corporate vice president of the Windows and Devices Group, posted the update on Twitter, as well as revealing that 90,000 unique PC or tablet models have upgraded to Windows 10 since launch.

He also said that people appear to be having fun with the Cortana feature, which has been asked to 'tell a joke' over 500,000 times.

Those with Windows 8 machines will need to run the free upgrade to Windows 8.1 before being able to download Windows 10.

Microsoft called the launch of Windows 10 a “new era for Windows” in which devices of all types and sizes run on a single platform.

“Our vision was one platform, one store and one experience that extends across the broadest range of devices from the smallest screens to the largest screens to no screens at all,” said Terry Myerson, vice president of Microsoft's Operating Systems group, in a blog post.

Most owners of Windows devices eligible for an upgrade should be able to run Windows 10 without issue as the minimum system requirements are quite low.

Windows 10 requires a 1GHz processor, at least 1GB of RAM for 32-bit or 2GB for 64-bit, and 16GB of hard drive space for 32-bit or 20GB for 64-bit.

Dell and HP had products running Windows 10 ready to go on 29 July as PC vendors look to Windows 10 to boost new hardware sales.

The most notable change in Windows 10 is the return of the Start menu in a reversion to the more familiar Windows environment that was lost in Windows 8 and 8.1.