We all know that the present determines the future, but what most of us do not consider is the magnitude of change in the future that small changes in the present cause. And that is what the butterfly effect is about. Small changes now lead to a very large change in the future.
Here's one of the best example of real life butterfly effect I found:
A Tunisian man named Mohammed Bouazizi, who made a living out of selling fruits and vegetables inspite of having a degree due to the high unemployment, was one day trying to sell his produce when a female police officer stopped him asking for the permit for selling. Upon his failure to produce it, she slapped him, spat at his face and confiscated his cart. Unable to bear the humiliation anymore, he went to the governors office demanding for his cart. Being refused, as a sign of protest and helplessness he lit himself on fire in the middle of the traffic.
Angered by this, starting from his friends and relatives and soon the public started protesting within hours. The protests grew from being a local one to national level protests, and within 10 days, the Tunisian president Ben Ali, ruler of Tunisia for 23 years had to leave the country with his family and thereby end his rule over the country. Inspired by this, protestors took to streets of Egypt, and in 2 weeks, led to the ouster of President Hosni Mobarak, putting an end to his 30 year rule. Subsequently, protests followed in several other Arab countries ranging from Libya which saw Gaddafi being killed, Syria where unrest still prevails and Bahrain too, which was later coined the Arab Spring.
And all this due to a police officer's slap.
And that is what butterfly effect is. A small, seemingly insignificant, change leads to a much much larger result.
If you think back on your life, you will discover that every major event in your life was triggered by very small events. Your choice of university, your career path, your meeting your spouse, your heroic actions, e.t.c.
Practically, this mean we can greatly improve our chances of big positive events in our lives by doing a lot more of positive small things. Smile more, be courteous to everyone, compliment more, read more, be helpful always, focus more on positive actions and you'll be setting yourself up for a good butterfly effect. You might win a big project because of the smile. You might find your life partner because of the little nice words and you will definitely make a lot more helpful friends because of your positive little actions. I believe that is where the quote "It's the little things that matter" come from.
So, please, smile more.