A complex system is a special class of system that has evolved to exhibit complexity, meaning that it is characterized by having a large number of different parts that are highly interconnected. All systems start simple and go through a process of evolution to become more complex. The evolution of complexity involves the process of differentiation, meaning the system comes to have more parts with those parts being more specialized, and integration meaning the parts become more interconnected and interdependent. Through this process of integration and differentiation during the system’s development, it comes to have a large number of diverse elements that are highly interconnected and interdependent, what we call complexity. Examples of complex systems include the global biosphere, urban networks, economies, logistics networks, cultures and many forms of social organization.