The classic, first program written in a new programming language. Originating in the C and Unix world, the program does nothing more than display "Hello World" on screen. It is often the first lesson in a tutorial, because it demonstrates how much code is necessary to write a very simple program.
In many languages, a complete framework of code is included with every program before anything is written by the programmer. The following example in C is what a programmer does write to display "Hello World" on two lines (each "\n" is a "new" line). The "printf" instruction outputs to the screen (go figure!).
printf ("Hello\nWorld\n");