An IPYNB file is a notebook document used by Jupyter Notebook, an interactive computational environment designed to help scientists work with the Python language and their data. It contains all the content from the Jupyter Notebook web application session, which includes the inputs and outputs of computations, mathematics, images, and explanatory text. IPYNB files can be exported to .HTML, .PDF, reStructuredText, and LaTeX formats.

IPYNB notebook documents are stored in the JSON plain text format, which makes it easier for them to be shared with colleagues and controlling versions. Also, IPYNB notebook documents available from a publicly accessible URL can be shared using the Jupyter Notebook Viewer with other colleagues without requiring them to install Jupyter Notebook on their machines. NOTE: Jupyter notebooks were formerly known as IPython notebooks, which is where the "ipynb" extension got its name. The file was created by IPython but is now used by the Jupyter Notebook app.