Often you'd want to execute a statement if a certain condition is
    met, and a different statement if the condition is not met.  This
    is what else is for.  else
    extends an if statement to execute a statement
    in case the expression in the if statement
    evaluates to FALSE.  For example, the following
    code would display a is bigger than
    b if $a is bigger than
    $b, and a is NOT bigger
    than b otherwise:
    
<?php
if ($a > $b) {
    echo "a is bigger than b";
} else {
    echo "a is NOT bigger than b";
}
?>