Microsoft's free Windows 10 upgrade offer expires on July, 29 2016. Here's what to do if you don't want to run Windows 10 right now, but want to take advantage of the the free upgrade before it runs out and still keep the version of Windows you're using now. (The free upgrade offer is available to anyone who is running a genuine version of Windows 7 or Windows 8.1.)

This article by Ed Bott outlines how to keep your existing Windows installation and still have access to the free Windows 10 upgrade, all free and legal. At its core, Ed says the process involves "claiming your entitlement under the free upgrade offer and then rolling back to your prior operating system. With that entitlement in place, you can schedule the final upgrade for when you're ready, even if that's after July 29."