Variables included in double-quoted strings will be interpolated. Their values will be concatenated into the enclosing strings. For example, two statements in the following PHP script will print out the same string:

<?php

$variable = "and";

echo "part 1 $variable part 2 ";

echo "part 1 ".$variable." part 2 ";

?>

This script will print:

part 1 and part 2

part 1 and part 2