How do models and simulations help us understand and improve our world?

Modeling and simulation (M&S) is the use of models - physical, mathematical, or otherwise logical representation of a system, entity, phenomenon, or process - as a basis for simulations - methods for implementing a model (either statically or) over time - to develop data as a basis for managerial or technical decision making. M&S supports analysis, experimentation, and training. As such, M&S can facilitate understanding a system's behavior without actually testing the system in the real world (source).

Big questions:

1. How do we create accurate and realistic models?
2. How do we create accurate and realistic simulations?
3. What is a visualization?

You should be able to create a sophisticated model and a simulation for almost any process you can imagine.