A command may refer to any of the following:
1. A command is a word or set of words that, when typed or in some cases spoken, cause the computer to perform a certain operation. For example, at an MS-DOS prompt when typing "dir" command the user would see a listing of files in the current directory.
2. When referring to a programming language, a command is a unique word used to perform a specific operation. For example, "print" is a command used to display text on the screen, entering the below command prints "Hello World!" to the screen, when the program or script is executed.
print "Hello World!";