Dynamical systems theory is a way of understanding how things in the world work and how they change over time. It's useful for studying things like weather, climate, and how populations of animals act. Basically, it looks at how the parts of something interact with each other. For example, it could be used to figure out how temperatures affect the number of people at a beach. By looking at the relationship between temperature and people, you can figure out how they both impact each other.