Update: I've published a newer version of this post.
If you are interested in getting started with Machine Learning, the [cached]TensorFlow Playground is a good way of building some intuition.
For a first introduction to the field, I recommend [cached]Neural Networks and Deep Learning, followed by the [cached]Deep Learning book.
To dive into a specific topic quickly, the [cached]TensorFlow tutorials are also great, Dive into Deep Learning has a lot of detail as well.
For Reinforcement Learning specifically, the standard text is [cached]Reinforcement Learning: An Introduction. Dave's [cached]UCL Course on RL is great too (playlist of all lectures).