What is a complex system?
To some, complexity science is merely the study of branches of different sciences, each with its own examples of complex systems (which are complex in ways that sometimes have nothing in common), while others argue that there is a single natural phenomenon called ‘complexity’, which is found in a variety of systems, and which can be the subject of a single scientific theory or approach. The difficulty of a complex system is that often its parts are interacting on many time and length scales. Examples of complex systems include the brain, bee hives, flocks of birds, the climate, and the economy.
For an 18 minute introduction to complex systems, watch my TEDx talk on Complexity.