Jupyter notebooks provide a document-based interactive environment for performing and recording computation. Notebook documents contain not only the code that is run, but prose and mathematics for describing the analysis, as well as recording the outputs of the computation, from plain text output to rich interactive media, such as HTML and javascript or images and video. Jupyter notebooks are being deployed widely as computational companions for publications, facilitation reproduction of results, and interactive exploration and modification of analyses, including by prominent scientific discoveries such as the LIGO experiment. Being freely available, open source software, Jupyter and IPython aim to improve the accessibility of reproducible practices in computational science.