Two (2) is a number that is significant for being the first and smallest prime number, and the only even one.
A number is called even if it is divisible by 2. In the decimal system, all such numbers have an 0, 2, 4, or 8 as their final digit.
2 is a very highly occurring number in human culture, because of the frequency of pairs and dichotomies. In particular:
- 2 is the number of genders in human beings and many other Earth species
- 2 is the number of people in a standard romantic relationship
- A common theme in works of fiction involves 2 individuals or groups in conflict, often "good" versus "evil"
- Sports and games often pit 2 teams or individuals against each other
- Parts of the human body often appear in duplicate:
- 2 ears
- 2 eyes
- 2 legs
- 2 arms
- 2 lungs
- 2 halves of the brain
- Upper and lower jaw
- A number added to the title of something to indicate that it is a sequel. For example, the sequel to Doom was titled Doom 2.
2 is notable for being the base of the binary numeral system, which some computers are built on.