Entropy is the literal, scientific tangibility of time. It is the arrow of time and all transformations in nature heading in its direction. And that direction is towards disorder, chaos and decay.
Entropy is the second law of thermodynamics, and it forms the basis for most physical laws. Entropy will always increase with time. Entropy can be thought of as the many ways in which something can be arranged. Take a puzzle for example. A puzzle can only be ordered in one way, and it takes energy to order it. But there are thousands of ways the pieces can be arranged in disorder. Despite disorder appearing to be the natural state of the universe, we exist. We exist in a way that is mathematically unprobable. There is an infinite number of ways our atoms could have been arranged that wouldn't result in life. But here we are, in all our complexity.