The Windows command interpreter.

:: To start a new instance of the command interpreter:
cmd

:: To run the specified command and then exit:
cmd /c "<command>"

:: To run the specified command and then enter an interactive shell:
cmd /k "<command>"

:: To disable the usage of 'echo' in command output:
cmd /q

:: To enable or disable command extensions:
cmd /e:<on|off>

:: To enable or disable file or directory autocompletion:
cmd /f:<on|off>

:: To enable or disable environment variable expansion:
cmd /v:<on|off>

:: To force output to use unicode encoding:
cmd /u