Also called the "return key," it is the keyboard key that is pressed to signal the computer to input the line of data or the command that has just been typed.

It Was the Return Key
The enter key was originally the "return key" on a typewriter, which caused the carriage to return to the beginning of the next line on the paper. In a word processing or text editing application, pressing the enter key (return key) ends a paragraph. A character code for return/end-of-line, which is different in Windows, Mac and Linux/Unix, is inserted into the text at that point. See CR/LF.