how to have multipe vars combine in php code example

Example 1: php glue strings

<?php
$a = "Hello ";
$b = $a . "World!"; // now $b contains "Hello World!"

$a = "Hello ";
$a .= "World!";     // now $a contains "Hello World!"
?>

Example 2: php concatenate two variables

$string = "the color is ";
$string .= "red";

echo $string; // gives: the color is red