The vast majority of Facebook’s users—83.5%—are outside the United States and Canada. To put that in context, there are estimated to be about 3.26 billion Internet users worldwide, a figure that’s growing rapidly. This means anything that trends on Facebook is a major indicator of what's shaking up the world.
So here is the top ten;
1.U.S Presidential elections
2. Paris Terror attacks
3.Syrian civil war and refugee crisis
5.Greek debt crisis
7.Fight against ISIS
8.Charlie Hebdo attack
10. Charleston shooting and flag debate
In addition to sharing its top 10 most talked about topics, Facebook also revealed the most talked-about entertainers, movies and shows of 2015:
Entertainer: Ed Sheeran
TV Show: "Game of Thrones"
Movie: "Star Wars: The Force Awakens"
Athlete: Floyd Mayweather, Jr.
Game: FIFA 15