Do you want to replace the existing 'Normal'?

I have MS Office installed on my Mac.

Very often, when I try to quit MS Word, I get this message, "Do you want to replace the existing 'Normal'?"

Huh? The existing 'Normal'? WTF is the existing 'Normal'?

And I have no idea whether I want to replace it.

Now, I don't know whether saying Yes or No or Cancel is going to have any impact on my documents. I just hit No most of the time. For kicks, one day I hit Yes and it showed me a folder where there was a file called which is some kind of a template. Now I didn't want to mess with that.

So, I canceled and ran for cover!