Explanation of the REM command. It is a BATCH command and CONFIG.SYS
COMMAND.

This command is designed to let you put remarks
into any batch file. This will not be executed and
they are only there for your or the user's convenience.
They can be used to put explanations into the Batch file.

Example: 
       This short program will only clear the screen. But
       it uses the REM command:
              echo off
              REM this will only clear the screen.
              cls