Supply a time stamp, get a time ago statement.

str_time.php

<?php
function str_time($stamp)
{
	$difference = time() - $stamp;
	$intervals = array(
		'minute' => 60,
		'hour'   => 3600,
		'day'    => 86400,
		'month'  => 2628000,
		'year'   => 31536000
	);
	$time_ago = 'Unknown time ago.';
	
	if($difference >= $intervals['year'])
		$time_ago = ((string) round($difference / $intervals['year'])).' years ago.';
	elseif($difference >= $intervals['month'])
		$time_ago = ((string) round($difference / $intervals['month'])).' months ago.';
	elseif($difference >= $intervals['day'])
		$time_ago = ((string) round($difference / $intervals['day'])).' days ago.';
	elseif($difference >= $intervals['hour'])
		$time_ago = ((string) round($difference / $intervals['hour'])).' hours ago.';
	elseif($difference >= $intervals['minute'])
		$time_ago = ((string) round($difference / $intervals['minute'])).' minutes ago.';
	elseif($difference < $intervals['minute'])
		$time_ago = ((string) $difference).' seconds ago.';
		
	return $time_ago;
}