Evolution

[simplexity]

Until relatively recently, a billion had always been 1,000,000,000,000 or one million million - literally one bi-million. Which makes much more sense when you consider how base ten counting actually works. By extension, one trillion - tri-million - would be one million million million and so on.

To put it another way: regardless of the exchange rate, you can have a new-billion English pounds, I'll settle for a proper-billion US dollars.

Here in the US 1,000,000,000 has always been a billion, although now I understand why it is different in the UK. How did you say 1,000,000,000 in the UK? This whole thing is mega confusing.
US Standard:
1,000: one-thousand
1,000,000: 1-million
1,000,000,000: 1-billion
1,000,000,000,000: 1-trillion
1,000,000,000,000,000 and up: a google