Display Time Since Post Was Published in WordPress

A small snippet from the WordPress Codex that displays the time since a post was published.
Add the following code to your functions.php file:

/**
 * Display time since post was published
 *
 * @uses	human_time_diff()  Return time difference in easy to read format
 * @uses	get_the_time()  Get the time the post was published
 * @uses	current_time()  Get the current time
 *
 * @return	string  Timestamp since post was published
 *
 */
function get_time_since_posted() {

	$time_since_posted = 'Posted ' . human_time_diff( get_the_time( 'U' ), current_time( 'timestamp' ) ) . ' ago';

	return $time_since_posted;

}

Then add the function inside the loop where you want it:

echo get_time_since_posted();

For another useful post meta display, see Display Estimated Post Reading Time.