Explained: Facebook Trending Topics and the controversy around it

Facebook’s trending topics shows popular topics being discussed at any given moment (Source: Facebook)
What’s behind the accusations that Facebook is manipulating its “trending topics” feature to promote or suppress certain political perspectives?
According to the technology blog Gizmodo, which is owned by Gawker Media, a former Facebook contractor with self-described conservative leanings said Facebook downplayed news that conservatives are interested in and artificiall