Unlike windoze linux does not care much about what the last part of the filename is. (making decisions about the type of a file based on it's name is a stupid idea anyway)
There is a program called "file" that guesses the type of files, and it pretty good at it.
Let's say you have a file called "foobar.zap" and you are wondering: "What the h*ll is this ?"
To find out you would say:
Code:
file foobar.zap
(on the command line in a terminal window)