Facebook says: &quot;The list of Trending Topics is then personalized for each user via an algorithm that relies on a number of factors, including the importance of the topic, <i>Pages a person has liked, location (e.g.. home state sports news), feedback provided by the user about previous Trending Topics</i> and what’s trending across Facebook overall. Not everyone sees the same topics at the same time.&quot; (My italics.)<p>If you&#x27;re interested in Iran, you will probably see stuff about Iran that hardly anyone else sees.<p>I have zero interest in Iran and have never seen anything about it.