A short scale billion is one thousand million.A long scale...

A short scale billion is one thousand million.
A long scale billion is one million million.
A short scale trillion is one million million (or one thousand short scale billion).
A long scale trillion is one million million million (or one million long scale billion).

Most of Europe and South America is long scale, while most English speaking are short scale. The UK was long scale until the 1970's, hence the alternative term "British billion" for a long scale billion. Britain now uses the short scale.

http://en.wikipedia.org/wiki/Long_and_short_scales#Long_scale_countries