$a = "hello"; $b = "world"; $c = $a . " " . $b; echo $c; // hello world
<?php $a = "Hello "; $b = $a . "World!"; // now $b contains "Hello World!" $a = "Hello "; $a .= "World!"; // now $a contains "Hello World!" ?>
$a = "Hello "; $a .= "World!";
$string3 = $string1 . $string2;