While Facebook is the most widely used social network in most countries, it’s not the biggest in every country, including China and Russia.
Facebook is the clear global leader, but in China and Iran, where Facebook is blocked, other approved networks have emerged. Facebook is not blocked in Russia, but users there prefer V Kontakte and Odnoklossniki.
The map of the #2 networks shows a different story — one where Instagram’s popularity (Instagram is owned by Facebook) is growing fast worldwide, while their primary competitor, Twitter, retains a strong foothold in Europe.
Now compare to the same map of most popular social networks in 2009. That was before Facebook went public and back when networks like Zing, Mixi and Friendster were still popular around the world.