Its an alias of DateTime::add()

We can add number of of days, months, years, hours and seconds with  a DateTime object.

Example

<?php

$date = new DateTime(“24-May-2011 20:15:22”);
echo $date->format(“d-m-Y H:i:s”).'<br />’;

date_add($date, new DateInterval(“P1Y”));
echo ‘<br />’.$date->format(“d-m-Y”).’ : I Year’;

?>

Output

24-05-2011 20:15:22

24-05-2012 : I Year