You can download the MacOS high sierra from the direct download link for your Mac computer, VirtualBox or Vmware. MacOS High Sierra is the fourteenth release of macOS which comes with a lot of upgraded features. If you are currently using MacOS older version then I have good news that you can upgrade your old OS with MacOS high sierra for free.
It is the second most widely used OS as per Wikipedia. MacOS is one of the most popular operating systems which is developed and market by App Inc.
