Complex systems research involves investigating the origin of systems with multiple interacting parts whose collective behavior cannot be simply inferred from the behavior of the individual components. In addition, complex systems research considers how parts of a system give rise to the collective behaviors of the system, and how the system interacts with its environment. Some example problems for complex system research are:

1. How the neurons of the brain give rise to consciousness and other mental activities
2. How the individual parts of a society give rise to an economy
3. How non-life gives rise to the first living system
4. How molecules control and regulate the development of whole organisms

Research in complex systems concerns the nature and consequences of interactions and non-linearities in systems of many objects. The field of complex systems cuts across all traditional disciplines of science, as well as engineering, management, and medicine. Complex systems includes topics such as artificial life, cellular automata, chaos, criticality, evolutionary computation, fractals, parallel computation, self-organization, and others.

Complexity:

1) ...the (minimal) length of a description of the system.

2) ...the (minimal) amount of time it takes to create the system.

The length of a description is measured in units of information. The former definition is closely related to Shannon information theory and algorithmic complexity, and the latter is related to computational complexity.

System:

A regularly interacting or interdependent group of parts forming a unified whole and delineated from the rest of the universe.

Complex Systems Links:

Complexity Online
A general source of information about complex systems, including the publication Complexity International Journal

Sante Fe Institute
An institution emphasizing multidisciplinary collaboration and focusing on what has come to be known as studies of complexity and complex adaptive systems

New England Complex Systems Institute
An independent educational and research institution dedicated to advancing the study of complex systems

Complex Systems Journal
Complex Systems was founded by Stephen Wolfram in 1987 to provide a publication forum for the new field of complex systems research.