Basically, you have the option to take the current trending topics and make it more localised. So if there’s something happening in America which is of no relevance to your area, it won’t be displayed in your Trending Topics because people from your area won’t be tweeting about it. Obviously, big global events such as the Haiti disaster or G8 meetings will attract attention from all over the world, but localised Trending topics can get quite annoying.
Twitter sums it up as follows:
“Twitter trends began as a way to shed light on popular conversations. It’s interesting to know that one topic can now spread across the world in real-time, and Trends help us discover which of those topics are paramount on a global scale.”
“The big events that come up around the world will always become a global conversation, but what about the big events that only happen in your world that only matter to those around you?
Source: http://www.mediapost.com