The easy answer is its simple grammar makes it easy for foreigners to pick up. The difficult answer is that colonialism spread the language all across the world, making it inevitable that it'd become the 'lingua franca'. At least, that's what I assume!

I agree with Tony, it goes back to the vastness of the British empire. Then as the British empire died the United States was starting its rise as a world power. Between the two, English seems to be solidly in place to be the primary global language for some time to come.

Hi! I have some reason:) (I think) The first thing is about history and it is most important reason. We knew long time ago, England is known with a lot of land in around the world and they said that England don't have sunset. Almost country belong England were taught English and use English like national language