How the way people code "Hello World" varies depending on their age and job:
High School/Jr.High

 10 PRINT "HELLO WORLD"
 20 END
 

First year in College

 program Hello(input, output)
 begin
 writeln('Hello World')
 end.
 

Senior year in College

 (defun hello
 (print
 (cons 'Hello (list 'World))))
 

New professional

 #include <stdio.h>
 
 void main(void)
 {
  char *message[] = {"Hello ", "World"};
  int i;
  for(i = 0; i < 2; ++i)
  printf("%s", message[i]);
  printf("\n");
 }
 

Seasoned professional

 #include <iostream.h>
 #include <string.h>
 class string
 {
  private:
   int size;
   char *ptr;
  public:
   string() : size(0), ptr(new char('\0')) {}
   string(const string &s) : size(s.size)
   {
     ptr = new char[size + 1];
     strcpy(ptr, s.ptr);
   }
   ~string()
   {
     delete [] ptr;
   }
   friend ostream &operator <<(ostream &, const string &);
   string &operator=(const char *);
 };
								     
 ostream &operator<<(ostream &stream, const string &s)
 {
   return(stream << s.ptr);
 }
 string &string::operator=(const char *chrs)
 {
   if (this != &chrs)
   {
     delete [] ptr;
     size = strlen(chrs);
     ptr = new char[size + 1];
     strcpy(ptr, chrs);
   }
   return(*this);
 }
 int main()
 {
   string str;
   str = "Hello World";
   cout << str << endl;
   return(0);
 }
 

System Administrator

 #include <stdio.h>
 #include <stdlib.h>
 main()
 {
  char *tmp;
  int i=0;
  /* on y va bourin */
  tmp=(char *)malloc(1024*sizeof(char));
  while (tmp[i]="Hello Wolrd"[i++]);
  /* Ooopps y'a une infusion ! */
  i=(int)tmp[8];
  tmp[8]=tmp[9];
  tmp[9]=(char)i;
  printf("%s\n",tmp);
 }

Apprentice Hacker

 #!/usr/local/bin/perl
 $msg="Hello, world.\n";
 if ($#ARGV >= 0) {
     while(defined($arg=shift(@ARGV))) {
         $outfilename = $arg;
         open(FILE, ">" . $outfilename) || die "Can't write $arg: $!\n";
         print (FILE $msg);
         close(FILE) || die "Can't close $arg: $!\n";
     }
 } else {
     print ($msg);
 }
 1;

Experienced Hacker

 #include <stdio.h>
 #include <string.h>
 #define S "Hello, World\n"
 main(){exit(printf(S) == strlen(S) ? 0 : 1);}
 

Seasoned Hacker

 % cc -o a.out ~/src/misc/hw/hw.c
 % a.out
 Hello, world.
 

Guru Hacker

 % cat
 Hello, world.

New Manager (do you remember?)

 10 PRINT "HELLO WORLD"
 20 END
 

Middle Manager

 mail -s "Hello, world." bob@b12
 Bob, could you please write me a program that prints "Hello, world."?
 I need it by tomorrow.
 ^D
 

Senior Manager

 % zmail jim
 I need a "Hello, world." program by this afternoon.

Chief Executive

 % letter
 letter: Command not found.
 % mail
 To: ^X ^F ^C
 % help mail
 help: Command not found.
 % damn!
 !: Event unrecognized
 % logout

Research Scientist

        PROGRAM HELLO
	PRINT *, 'Hello World'
	END

Older research Scientist

	WRITE (6, 100)
    100 FORMAT (1H ,11HHELLO WORLD)
	CALL EXIT
	END