A friend recently told me she now has Windows 10 - which she didn't want. It did not care for her wants or wishes, however; it just went ahead and installed itself.

If you're running Windows and would like to avoid the same thing happening, you can use the GWX stopper tool - explanations and download link can be found here.

If you're guessing now that I am using this thing, you're completely right - I would like to decide myself when to change operating system, thankyouverymuch!