Twitter has updated the algorithm behind its Trending Topic to give more weightage to the "most breaking" and "immediately popular" topics rather than constantly popular items.
Twitter has introduced this change in the algorithm so that the Trending Topic retains (or should I say improve) its relevance. For quite some time now, Twitter's Trending Topics have always been dominated by (spams ?) constantly popular items like Justin Bieber. This has reduced the usefulness of the Trending Topic, which is supposed to "reflect what new or newsworthy topics are occupying the most people's attention on Twitter at any one time".
This is what Twitter wrote regarding the change:
Twitter is about what is happening right now, and we have recently updated our trending topics algorithm to reflect this. The new algorithm identifies topics that are immediately popular, rather than topics that have been popular for a while or on a daily basis, to help people discover the "most breaking" news stories from across the world. (We had previously built in this 'emergent' algorithm for all local trends, described below.) We think that trending topics which capture the hottest emerging trends and topics of discussion on Twitter are the most interesting. While this is very much a work in progress, with this tweak we have taken a big step toward capturing how trends quickly emerge and grow on Twitter. We also think it's compelling to know what the "most popular" topics are, and we will look to capture this in some way in the future.
It is important to note that this new algorithm does not "block" any topics from trending. If topics you saw regularly in your Trending Topics menu have disappeared or are not showing as consistently as before, do a saved search for them on your homepage. That way, in one click, you can view search results for topics that matter most to you. Also consider localizing your Trending Topics menu, as shown below.
Twitter explicitly states that no topic is blocked. This is in response to the fans of Justin Bieber who have been complaining that Beiber has been blocked from the Trending Topic.
This change is something that Twitter should have introduced a long time ago - back when everyone was starting to get annoyed with Justin Bieber constantly in the Trending Topic . Nevertheless, it is sure to make Trending Topics interesting again.