2 variables stick together 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