0 (
zero; is both a
number and the
numerical digit used to represent that number in
numerals. The number 0 fulfills a central role in
mathematics as the
additive identity of the
integers,
real numbers, and many other
algebraic structures. As a digit, 0 is used as a placeholder in
place value systems.
Names for the number 0 in English include
zero,
nought (UK),
naught (US),
nil, or—in contexts where at least one adjacent digit distinguishes it from the letter "O"—
oh or
o. Informal or slang terms for zero include
zilch and
zip.
Ought and
aught as well as
cipher, have also been used historically.