
Integers are the counting numbers and their negatives . . . . . .
Wikipedia: Integer
Mathworld: Integer
Fact archive: Integer
Math League: integers, whole numbers and their properties (Using Whole Numbers, Place value, Expanded form, Ordering, Rounding whole numbers, Divisibility tests; Operations and their properties: commutative, associative, distributive, zero property, identity, order of operations (PEMDAS))
Construction  Construction of sets of numbers, starting with the original Peano Axioms, formulated so that zero is included in the set of natural numbers. (See Is Zero a Natural Number?)
The webmaster and author of this Math Help site is Graeme McRae.