Windows 7 remains the operating system installed in PCs worldwide, followed by Windows 8.1 and Windows XP, according to data released by NetMarketShare. Windows OS is on more than 90% of the computers in the world. The July 29 release of Windows 10 should cement Microsoft's hold on computers, though the company has faced several challenges in breaking into the mobile market.

Microsoft's operating system runs on 90.85% of the computers identified by NetMarketShare, well ahead of the 7.54% for Mac OS and 1.61% for Linux.

Windows 7 is the most popular (60.98%), ahead of the newer version of the system, Windows 8.1 (13.2%) and, even more surprising, Windows XP (11.98%). In comparison, the most recent version of Mac OS X, Yosemite, is only running on 4.54% of the computers surveyed.

With the launch of the latest version of its operating system, Microsoft willtry to convince Windows 7 clients to upgrade to 10. To help accomplish this, Microsoft has already announced that for the first year, upgrades from Windows 7 and 8.1 to 10 will be free.

Windows 10 for PC and tablets will come out on July 29.