In this talk, I will give a quick introduction to an aspect of numerical astronomy that has exploded over the last decade: cosmological simulations. I will discuss their many forms, e.g., N-body simulations, cosmological simulations, hydrodynamical simulations, isolated merger simulations, and constrained realisation simulations. Why do we need them and how do we interpret them? I will briefly overview their history, how to put a cosmological simulation together, and, importantly, what kind of things we should look out for when comparing against the various cosmological simulations out there in the community.
As an aside, numerical simulations can also be art! How to get numerical astronomy to the public has always been a difficult task. I will mention some outreach projects we have done with the simulations over the years, such as projection light shows, galaxy builders, and virtual reality.