In batch files, you can launch programs. For example, a batch file might need to launch Microsoft Paint, Calculator, and Notepad and thus contain the lines

mspaint
calc 
notepad 

However, these programs won't be run at the same time. Notepad will run only after you close Calculator—and Calculator will run only after you close Paint.

If you want the programs to be executed at the same time, you can use the Start command to run them. In this example, you'd include the lines

Start mspaint 
Start calc 
Start notepad 

in the batch file.

Another way to launch programs simultaneously from batch files is to use the pipe (|) symbol. The pipe symbol is designed to transfer the output of one command to another command for use as input. However, when you use it in the line

mspaint | calc | notepad 

the result is the simultaneous execution of the three programs.

—Murat Yildirimoglu