Introduction To Variables And Naming Rules

<?php

  /*
    Variables
    - Naming Rules + Info
    [1] Start With Dollar Sign $
    [2] Start With A Letter [a-z] Or [A-Z] Or Underscore
    [3] You Can Use Numbers Inside The Name
    [4] No Special Characters Allowed
    [5] Case Sensitive
    - Test Single And Double Quotes

    Search
    - Loosely Typed Language
  */

  $username = "Osama";
  $Username = "Elzero";

  echo $username;
  echo '<br>';
  echo $Username;
  echo '<br>';
  echo 'Hello $username';
  echo '<br>';
  echo "Hello $username";