The most common way of writing Python code is using .py files. An alternative to .py are so called “notebooks” (extended with .ipynb) . They are not only another file format, but most of all a different philosophy of writing (not only) Python code.

What is a notebook?

A notebook (.ipynb file) is actually a JSON file which contains Python code (and/or Markdown text) organized in so called “cells”. When you open the file in an editor that supportsthe .ipynb format you’ll see something like this:

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After running a single code cell, it is sent to the IPython kernel and executed.

Editors with notebook support

  • Jupyter Notebook
  • Jupyter Lab
  • Google Colab
  • PyCharm (read only in the free version)
  • Visual Studio Code

and more.

Many .ipynb editors (especially when they use cloud) work in a browser.

Notebook key features

  • code and text support
  • each cell of code (or Markdown text) can be run separately
  • order of cells doesn’t matter, order of running them does
  • keyboard shortcuts for actions like: adding and deleting cells, navigating through the notebook, executing code

Applications

Jupyter Notebook isn’t a universal code editor. It’s not well-suited for writing production code. However, there are numerous use cases where Jupyter proves to be a valuable tool, such as:

  • prototyping
  • experiments
  • data analysis
  • education

Keyboard shortcuts

When you escape the cell (by pressing Esc, of course), you switch it to command mode. Now you can use a number of keyboard shortcuts which allow you to perform various operations on the cell, e.g.:

  • creating a new cell above (a) or below (b)
  • deleting a cell (double d)
  • moving between cells (arrow up ↑, arrow down ↓)
  • executing a cell (Shift + Enter / Ctrl + Enter / Alt + Enter)

If you want to enter the cell again (switch to edit mode) – press Enter.