An instruction to a computer or device to perform a specific task.Commands come in different forms. They can be:
buttons or other graphical objects on your screen
Every program that interacts with people responds to a specific set of commands. The set of commands and the syntax for entering them is called the user interfaceand varies from one program to another.
The DOSoperating system makes a distinction between internaland external commands.Internal commands are commands, such as COPY and DIR, that can be handled by the COMMAND.COM program. External commands include thenames of all other COM files, as well as EXE and BAT files.