Abstract: Understanding infinity lead mathematicians in discovering new ideas, developing new methods and getting new insights into mathematical notions and constructions. I will discuss the introduction of infinity to the mathematical world, and go in depth into how huge of a role the infinite plays in calculus, number theory and set theory. Ultimately, I would like to help turn a `hugely' important and difficult concept into an idea we can understand. Also I will highlight that, even now, how little we know about infinity. .