A study of many physical phenomena like the weather, stellar motion, even water falling from a faucet has revealed results that are totally random and impossible to predict. The unpredictability has been termed as the Chaos Theory.
An important conclusion from studies with the Chaos theory is that even a small, insignificant change in the initial conditions can create large changes in the final outcomes. This is due to the fact that at every stage the results change in a exponential manner depending on the conditions prevailing in the previous stage.
The Butterfly Effect is an exotic term coined to describe the effect of the unpredictability of the Chaos theory. Even an insignificant event like a butterfly flapping its wings in a forest in one corner of the Earth can be the reason behind a tornado occurring on the other side of the planet.
The butterfly effect is a term used in Chaos Theory to describe how tiny variations can affect giant systems, and complex systems, like weather patterns. The term butterfly effect was applied in Chaos Theory to suggest that the wing movements of a butterfly might have significant repercussions on wind strength and movements throughout the weather systems of the world, and theoretically, could cause tornadoes halfway around the world.
What the butterfly effect seems to posit, is that the prediction of the behavior of any large system is virtually impossible unless one could account for all tiny factors, which might have a minute effect on the system. Thus large systems like weather remain impossible to predict because there are too many unknown variables to count.
The term "butterfly effect" is attributed to Edward Norton Lorenz, a mathematician and meteorologist, who was one of the first proponents of Chaos Theory. Though he had been working on the theory for some ten years, with the principal question as to whether a seagulls’ wing movements changes the weather, he changed to the more poetic butterfly in 1973.