File Types:

There are many type of files that reside in the Windows™ 
directory structure. Listed below are the major types with 
a brief explanation:

BMP - BitMaP graphic file

COM - program file

DOC - text (ASCII) file

DLL - Dynamic Link Library used by the Windows programs

DRV - drives (runs) a device (printer,video) in Windows

EXE - program file

ICO - icon (picture) file

INI - define the Windows environment

GRP - window containg icons representing programs, etc.

HLP - file containing help documentation

PCX - paintbrush graphic file

PIF - Program Information File for non-Windows applications

SYS - file containing data for running DOS

TRM - file containg configuration information for Terminal

TXT - text (ASCII) file

WRI - text file created by Write

WAV - sound file