A billion is a number with two distinct definitions:
- 1,000,000,000, i.e. one thousand million, or 10^9, as defined on the short scale. This is now the meaning in both British and American English.
- 1,000,000,000,000, i.e. one million million, or 10^12, as defined on the long scale. This is one thousand times larger than the short scale billion, and equivalent to the short scale trillion. This is the historical meaning in English and the current use in many non-English-speaking countries where billion and trillion 10^18 maintain their long scale definitions.
Nevertheless almost everyone uses 1B = 10^9 for technical discussions
