Billion

From Wikipedia

In Canada and in the U.S. one billion equals 1,000,000,000, or 10⁹, or one thousand millions.

In most other countries, one billion equals 1,000,000,000,000, or 10¹², or one million millions. The American billion is called one milliard in these countries.

Britain and Australia traditionally employed the international usage, but have recently largely switched to the U.S. version.