Jupyter Notebook is an open-source web application that allows users to create and share documents containing live code, equations, visualizations, and narrative text. It supports various programming languages, including Python, R, and Julia, making it a versatile tool for data analysis, scientific research, and educational purposes. Users can write code in cells, execute it, and see the results immediately, which facilitates an interactive coding experience. Jupyter Notebooks are widely used in data science and machine learning, as they enable easy documentation and presentation of workflows, making complex analyses more accessible and understandable.