Jupyter Notebooks at their core are just JSON documents that contain all your code, markdown styles and outputs. Yet when you run a notebook, there's a lot that's happening under the hood - from starting a session with the notebook server, to launching an IPython kernel, and a rich Web UI communicating with the notebook server and the IPython kernel using Jupyter's REST APIs and ZMQ websockets. We will explore the Jupyter ecosystem (Jupyter, JupyterLab, JupyterHub) and see how this system comes together.