18 is the age limit for being allowed a driver's license and/or for purchasing tobacco in many parts of the world. It is also the voting age in the vast majority of countries around the world today. During the Vietnam War, Americans could be drafted at an age as low at 18, but were not allowed to vote in most states until they were 21. A movement spread to lower the voting age, and in 1971 the Twenty-sixth Amendment extended a guarantee of suffrage to anyone 18 years or older in all states. The voting age was lowered from 21 to 18 in the U.K and many other nations around that time. 18 is also the age in most countries at which a person may appear in a pornographic video, if pornography is legal at all, or have sex with a person in a position of authority over them (a teacher, athletic coach or employer, for instance).
There are eighteen wheels on an 18-wheeler, or Mack truck.
See also: sixteen, seventeen, eighteen, nineteen, twenty, integer, list of numbers.
This article is about the number. For the year AD 18, see 18.
18 is also the title of an album by Moby; see 18 (album).