Windows 10 is the most current version of Microsoft's flagship OS after first launching two years ago.

However, despite this it is not the most popular Windows OS out there for PC fans.

According to NetMarketShare, Windows 7 is used by more PC users than Windows 10 - with the eight year-old OS having a market leading 47.21 per cent share.

This is compared to the second most popular PC OS, Windows 10, which has a 29.09 per cent chunk of the operating system market.

While Windows 8.1 and Windows XP have an operating system market share of around five per cent each.

However, for the huge amount of PC owners using an earlier version of Windows, they’ve been given a stark warning as to why they need to upgrade to Windows 10 as soon as possible.

The Register has reported that Microsoft have been patching out security bugs in Windows 10 but NOT immediately rolling those out to Windows 7 and 8 users.

This lag in updates leaves potentially hundreds of millions computers at risk of an attack.

The exploits that hackers and malware are taking advantage of is being fixed in the big Windows 10 releases.