Systems science is a way of thinking about how different parts of the world relate to and influence each other. It looks at how things like machines, animals, people, and nature all work together to create a system that is more than the sum of its parts. It also looks at how changes to one part of a system can have an effect on other parts of the system. For example, if you have a tree in a forest, a change to the tree, like cutting it down, might affect other parts of the forest, like the plants and animals that live in it.