What is Reinforcement Learning?

When people refer to AI today, some of them think of Machine Learning, while others think of Reinforcement Learning. I fall into the second category. I always saw Machine Learning as statistical models that have the ability to learn some correlations, from which they make predictions without being explicitly programmed.

While this is, in some way, a form of AI, Machine Learning does not include the process of taking actions and interacting with an environment like we humans do. Indeed, as intelligent human beings, what we constantly keep doing is the following:

1. We observe some input, whether it's what we see with our eyes, what we hear with our ears, or what we remember in our memory.
2. These inputs are then processed in our brain.
3. Eventually, we make decisions and take actions.

This process of interacting with an environment is what we are trying to reproduce in terms of Artificial Intelligence...