Zero 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.
There are difrent words used for the number or concept of Zero depending on the context. For the simple notion of lacking, the words nothing and none are often used.
Sometimes the words nought, naught are used. Several sports have specific words for Zero, such as Nil in football, Love in tennis and a duck in cricket. It is often called oh in the context of telephone numbers.