simple meaning of explode and implode in php

Explode split a string by string,it change a string into array,implode means return a string from the elements of an array.

example of explode.
<?php
$text= "one two three";
$res= explode(" ", $text);
echo $res[0]; // one
echo $res[1]; //two
?>
example of impode.

<?php
$test= array('one', 'two', 'three');
$res = implode(",", $test);
echo $res ; // one,two,three

?>