Penguin

This is the default introductory program to a new ProgrammingLanguage. It simply prints the text “Hello World” and a newline.

HelloWorld is not really meant as a sample program, though. What you learn from creating a Hello World program is how to use the language tools: it's a first exercise in entering, compiling and running a program on a paticular system, and it might make you go find the documentation on the I/O library in some cases. In many very high level languages, it looks exactly the same.

As a demonstration of the feel of a language, PPR:WardNumber is a much better problem. 99 Bottles of Beer on the Wall can also be adequate.

Some examples of HelloWorld in different ProgrammingLanguages:

BASIC:
PRINT "Hello World\n"
C:
#include <stdio.h>
int main(int argc, char **argv) {
    printf("Hello World\n");
    return 0;
}
C++:
#include <iostream>
int main (int argc, char *argv[]) {
    std::cout << "Hello World" << std::endl;
    return 0;
}
COBOL:

I'm not sure how much of this is serious or facetious...

000100 IDENTIFICATION DIVISION.
000200 PROGRAM-ID. HELLOWORLD.
000300 DATE-WRITTEN. 02/05/96 21:04.
000400* AUTHOR BRIAN COLLINS
000500 ENVIRONMENT DIVISION.
000600 CONFIGURATION SECTION.
000700 SOURCE-COMPUTER. RM-COBOL.
000800 OBJECT-COMPUTER. RM-COBOL.
000900
001000 DATA DIVISION.
001100 FILE SECTION.
001200
100000 PROCEDURE DIVISION.
100100
100200 MAIN-LOGIC SECTION.
100300 BEGIN.
100400 DISPLAY " " LINE 1 POSITION 1 ERASE EOS.
100500 DISPLAY "HELLO, WORLD." LINE 15 POSITION 10.
100600 STOP RUN.
100700 MAIN-LOGIC-EXIT.
100800 EXIT.

Java

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello World");
    }
}
Linux x86 AssemblyLanguage:
.data
.align 4
message::
  .string    "Hello World\n"
message_len = . - message

.text
.align 4
.globl _start
_start::
   movl $0x4, %eax
   movl $0x1, %ebx
   movl $message, %ecx
   movl $message_len, %edx
   int  $0x80
   movl $0x1, %eax
   xorl %ebx, %ebx
   int  $0x80
Perl:
print join('', pack("V4", (0x6c6c6548,0x6f77206f,0xa646c72)));

Sorry, someone is being facetious. Of course, it's:

print "Hello World\n";
Python:
print "Hello World"
UserRPL (for the HP48 Calculator):
<< "Hello World" MSGBOX >>
PHP:
<?php
echo("Hello World\n");
?>

And the list could go on and on.

See also: