Editing and navigating a notebook

When we open a notebook (by either clicking on its name in the dashboard or creating a new notebook), we see the following in the browser window:

In the preceding screenshot, from the top to the bottom, we see the following components:

• The Title bar (area marked 1) that contains the name of the notebook (in the preceding example, we can see Chapter 2) and information about the notebook version
• The Menu bar (area marked 2) looks like a regular application menu
• The Toolbar (area marked 3) is used for quick access to the most frequently used functionality
• In the area marked 4, an empty computation cell is shown

Starting with IPython Version 2.0, the notebook has two modes of operation:

• Edit: In this mode, a single cell comes into focus and we can enter text, execute code, and perform tasks related to that single cell. The Edit mode is activated by clicking on a cell or pressing the Enter key.
• Command: In this mode, we perform tasks related to the whole notebook structure...