This is a free, online wikibook, so it is continaully being updated and refined. According to the authors, "Systems theory focuses on complexity and interdependence. A system is composed of regularly interacting or interdependent groups of activities/parts that form a whole. Part of systems theory, system dynamics is a method for understanding the dynamic behavior of complex systems. The basis of the method is the recognition that the structure of any system -- the many circular, interlocking, sometimes time-delayed relationships among its components -- is often just as important in determining its behavior as the individual components themselves. Examples are chaos theory and social dynamics."