The map above shows where people live relative to their Facebook friends. Each line connects cities with pairs of friends. The brighter the line, the more friends between those cities.
It is interesting to see which areas are very bright (USA and Western Europe), but also fascinating to see massive areas of darkness where facebook has still not taken off, or population density is low.
Why do you think India is bright, but China is dark?
How about Australia – why are there only certain bright bits?