An integer is a number that can be written without a fractional component.
The set of integers consists of zero (0), the natural numbers (1, 2, 3, ...), and their additive inverses (-1, -2, -3, ...).
Integer numbers could be written as:
$ ...,-5,-4,-3,-2,-1,0,1,2,3,4,5,... $
Set of integer numbers is denoted by the letter ℤ
Set of integer numbers can be written down as:
ℤ
$ = \{...,-5,-4,-3,-2,-1,0,1,2,3,4,5,... \} $