Complexity is usually confused with the term complicated. There are many different elements, individuals and particles in a complex system that interact with each other. They also respond to the environments. These elements, individuals and particles are inter-genius in terms of the information, knowledge or otherwise. Interaction involves interchanging information and knowledge. There is no central control or a centralized processing unit in a complex system. We are surrounded by complex systems, for example, our brain, the biosystem, immune system, traffic, the financial system, society, social media, economy, etc. are all complex systems. It can also be seen in a different branch of academics such as physics, mathematics, biology logistics, sociology, etc. Discussions amongst various intellectuals reveal that different complex system in different environments has certain things in common. They need a common methodology or a common language to be analyzed and described.
