It is branch of mathematics mainly to deal with complex systems but very useful at other places like social sciences, biology, environmental science etc.
Chaos theory is about one single change in the conditions of an event or agent in complex system can create massive changes in the outcome of that event or agent. This teaches us expect the unexpected if sorrounded by things which are really connected with one another and complexity of system is beyond our imagination or calculation. We always surrounded by such systems ,like weather is a complex system, our body is a complex system because no one always sure about what chemistry is happening in our body, our society is also a example of complex system , stock market is a complex system.
Few characters of complex systems are-
- Interconnection
- Adoptation and learning
- Non linear
We blame sometimes to ourselves about what we have done previously and we should have done something else, in that it's not your fault but you become victim of complex system.
Many people will think that if everything is like that then there is no point to blaming or correcting someone. Nope. Point is if faced with any problems like in chaos theory and you know you are part of complex systems then try to change the initial conditions for the betterment of the outcome.
Fooled by Randomness by Nicholas Taleb is also a great book on expecting the unexpected.
Thinking slow and fast is also teaches how to less rely on expert intuition in complex and un -predictable systems.
Butterfly effect is also one of the part of chaos theory. I have explained butterfly effect as well in one of my posts.