You will find Windows 8 on a notebook (AKA laptop) or desktop computer to be confusing and difficult to use. Windows 8 is a completely different design. It is a version of Windows that bears no resemblence to the Windows you have seen or used before. It is designed to be used on a hand-held panel (like an iPad) with your fingers, not on a normal personal computer with a mouse and keyboard.
Windows 10 is an advancement on Windows 8. It is everything that Windows 8 was, but worse.
You can no longer buy Windows 7 in a new computer. If you have one that runs it, take good care of it.
Support end dates for Vista is April 11, 2017 and Windows 7 is January 14, 2020.
If your system uses Vista or Windows7 — BE HAPPY!