I can't quite figure it out. Personally, I would be lost without file extensions. How do you know what program to open files up in? How do you tell the difference between pictures and text files?

I was all set to put this “Windows Explorer Explained” series to rest for a while, but then reader Martin wrote in with a question that comes up a lot: in Windows 7, how do you reveal the hidden file ...

What about some kind of a extension database? I am thinking of a simple text file that can be appended by each software program upon install to the OS that will state what the file extension is by ...