Jupyter is an integrated development environment that uses a notebook interface. It was originally developed for Python, but is now available for a variety of other languages, including my favorite, R. I attended a talk about Jupyter from one of the main developers, and after explaining what Jupyter is, he demonstrated JupyterLab. JupyterLab is a new IDE that uses the same structure and files as Jupyter. It looks to be very simple but also very powerful.
The JupyterLab Team and Project Jupyter. JupyterLab is Ready for Users. Jupyter blog, February 20, 2018. Available at https://blog.jupyter.org/jupyterlab-is-ready-for-users-5a6f039b8906.