What defines a miracle? Everything in this world is controlled by Hashem. There is no difference between Hashem's ability to make plants grow or split the sea. What differentiates the two? The answer is that Hashem created a natural order in the world to allow people to believe that Hashem does not exist. An event that breaks the rules is called a miracle. It is Hashem showing us a glimpse of His total control.
Nature is called Teva from the word Tava or drowning. The everyday miracles that Hashem performs in nature and to us individually are drowned beneath the surface, and out of our field of view unless we use our mind to perceive them. The word for a miracle is Nes. Nes means a flagpole. It is an event that stands out in plain view for all to see, unless one chooses to look the other way.
On a similar note the world was created to challenged us to choose good. The word for these challenges is Nisayon. Nisayon has the word Nes in it. What is the connection? The answer says Rav Chaim Zaitchek, is that we all are born with great potential for good. Our challenge is to dig deep down and use these abilities. We are tested as a means to bring this potential out into the world. A Nisayon is an opportunity to show ourselves, Hashem, and the universe the good buried within us. By passing a Nisayon we have created a Nes!