What is a simple definition of entropy and how does it relate to chaos theory?
We have different types of entropies, such as entropy of the system, entropy of the surroundings and they both represent the entropy of the universe.
Note that the relationship between the changes in entropy is the following:
The second law of thermodynamics states that The entropy of the universe always increases.
Here is a video that explains entropy in more details:
Thermodynamics | Spontaneous Process & Entropy.