Most of the answers seem focused around converting the date from a string to time. It seems you're mostly thinking about getting the date into the '5 days ago' format, etc.. right?
This is how I'd go about doing that:
$time = strtotime('2010-04-28 17:25:43');
echo 'event happened '.humanTiming($time).' ago';
function humanTiming ($time)
{
$time = time() - $time; // to get the time since that moment
$time = ($time<1)? 1 : $time;
$tokens = array (
31536000 => 'year',
2592000 => 'month',
604800 => 'week',
86400 => 'day',
3600 => 'hour',
60 => 'minute',
1 => 'second'
);
foreach ($tokens as $unit => $text) {
if ($time < $unit) continue;
$numberOfUnits = floor($time / $unit);
return $numberOfUnits.' '.$text.(($numberOfUnits>1)?'s':'');
}
}
I haven't tested that, but it should work.
The result would look like
event happened 4 days ago
or
event happened 1 minute ago
cheers