how to combine 2 variables into 1 in php code example

Example 1: assign multiple variables php

[$var1, $var2, $var3, $var4, $var5] = array(1, 2, 3, 4, 5);

Example 2: php concatenate two variables

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

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