concatenation in php

<?php

$name='php';
$version='5.4';
$use='for web development';

echo  'hai the ';
echo   ' ';
echo  $name;
echo   ' ';
echo  $version;
echo   ' ';
echo  $use;

 // for new line

echo '<br>';


//      "." use for concatenation

echo 'hai the '.$name.' '.$version.' '.$use;
?>


output :

hai the php 5.4 for web development
hai the php 5.4 for web development