JupyterLab: A Quick Introduction

This is a short reference page for learners who have never used JupyterLab before. It covers only what you need to get started.

Images and content on this page are adapted from the CodeRefinery Jupyter lesson (CC-BY).

What is JupyterLab?

JupyterLab is the next-generation browser-based interface for Jupyter Notebooks. It is highly modular and customisable. You open it in a regular web browser (Chrome, Firefox, Safari) — even when it is running on your own laptop, no internet connection is required for local use.

Inside JupyterLab you work with notebooks (files ending in .ipynb). A notebook combines code, its output, and narrative text in a single document:

Components of a Jupyter notebook. (CC-BY, CodeRefinery)

The interface

JupyterLab user interface: left side toolbar with a file browser and optional Git tab; right side shows open files and notebooks. Split view is possible by dragging a tab. (CC-BY, CodeRefinery)

Left-hand sidebar (toggle with Ctrl-b, or ⌘-b on Mac):

• File browser — create launchers, folders, upload files

• Running terminals and kernels

• Command palette

• Open tabs

• Git integration (if the jupyterlab-git extension is installed)

Main work area — notebooks, terminals, and consoles open here as tabs. You can drag tabs to view files side by side.

Menu bar — File, Edit, View, Run, Kernel, and Help menus at the top.

Types of cells

Every notebook is made of cells. There are two types you will use:

• Markdown cells — contain formatted text written in Markdown

• Code cells — contain code to be interpreted by the kernel (Python, R, Julia, …)

Markdown cell example

## Second level heading

This cell contains simple **bold**, *italics*, and `inline code`.

* bullet points

or

1. numbered
2. lists

Equations: $e^{i\pi} + 1 = 0$

Links: [Markdown cheatsheet](https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet)

Code cell example

# A code cell runs statements of code.
# The output appears directly below the cell.
print("hello world")

Command mode and edit mode

• Edit mode — press Enter or double-click a cell to type inside it (cursor visible)

• Command mode — press Escape or run the cell to navigate between cells (no cursor)

Most keyboard shortcuts only work in command mode. If a shortcut is not responding, press Escape first.

Keyboard shortcuts

Cell shortcuts

Shortcut	Effect
Enter	Enter Edit mode
Escape or Ctrl-m	Enter Command mode
Ctrl-Enter	Run the cell
Shift-Enter	Run the cell and select the cell below
Alt-Enter	Run the cell and insert a new cell below
m / y	Toggle between Markdown and Code cell (command mode)
d-d	Delete a cell (command mode)
z	Undo deleting (command mode)
a / b	Insert cell above / below current cell (command mode)
Up / Down or k / j	Select previous / next cell (command mode)

Notebook shortcuts

Shortcut	Effect
Ctrl-s (or ⌘-s)	Save notebook
Ctrl-b (or ⌘-b)	Toggle left-hand sidebar
Shift-Ctrl-c	Open command palette

See also

For the full CodeRefinery Jupyter lesson including exercises and more detail: https://coderefinery.github.io/jupyter/