A Jupyter Notebook by default is identified by the .ipynb extension. Upon clicking on the name of once such notebook in the file manager provided by Jupyter, you'll be presented with a screen resembling the following:
The topmost section, where you can see a menu bar, a toolbar, and the title of the notebook, is called the header. On the right side of the header you can see the environment in which the notebook is executing, and when any task is running, the white circle beside the environment language's name turns gray.
Below the header is the body of the notebook, which is composed of cells stacked vertically. Each cell ...
