An axiom is simply a statement that is defined as being true. Often times on grounds of being self-evident. For example, one of Euler's axioms is "Things that a

An axiom is simply a statement that is defined as being true. Often times on grounds of being self-evident. For example, one of Euler's axioms is "Things that are equal to the same thing are also equal to one another". Whereas Euler's may seem pretty tame, the Axiom of Choice is not. That's why some people think it might be wrong.