Guess The Number Tutorial

<?php
//Starts our php document
if (!$x)
//if we have already defined x and started the game, this does not run
{
Echo "Please Choose a Number 1-100 <p>";
//gives the user instructions
$x = rand (1,100) ;
//creates x
}

What this code does, is check to see if the game has already started. If it has, all of this is ignored. If it has not, then it randomly chooses a number to be the winning number, $x. It also prints some brief instructions for the user.