1,000,000,000 (one billion, short scale; one thousand million or milliard, yard, long scale) is the natural number following 999,999,999 and preceding 1,000,000,001. One billion can also be written as b or bn.
|Cardinal||One billion (short scale)|
One thousand million, or one milliard (long scale)
|Ordinal||One billionth (short scale)|
|Factorization||29 · 59|
One billion years may be called an eon in astronomy or geology.
Previously in British English (but not in American English), the word "billion" referred exclusively to a million millions (1,000,000,000,000). However, this is no longer common, and the word has been used to mean one thousand million (1,000,000,000) for several decades.
The term milliard can also be used to refer to 1,000,000,000; whereas "milliard" is rarely used in English, variations on this name often appear in other languages.