Batch files are text files, having ‘BAT’ as extension. The word batch means group, hence a batch file is a group of commands. It is like a program, which executes all commands one-by-one. For example AUTOEXEC.BAT is a batch file, which is executed every time, computer is started. Running a batch file is simple just type its name (the extension isn’t needed) at a DOS prompt, and DOS will run it by executing all the commands in it.