In computing, start is a command of the IBM OS/2,[1] Microsoft Windows[2] and ReactOS[3] command-line interpreter cmd.exe[4] (and some versions of COMMAND.COM) to start programs or batch files or to open files or directories using the default program.

The command is also one of the basic commands implemented in the Keyboard Monitor (KMON) of the DEC RT-11 operating system.

[5] The TOPS-10[6] and TOPS-20[7] operating systems also provide a start command.

It is used to start a program in memory at a specified address.

B Starts the command or program without creating any window.