## Working with IPython (Google Colab) Cells (Jupyter Notebook) In this lesson, we will learn how to work with cells in Google Colab or Jupyter Notebook. Each cell represents a unit of code that we can write and execute. To add code to a cell, we can simply type in the cell like this: ```python print("hi") ``` Then, we can go to the "Runtime" menu and choose "Run selection." Google Colab and Jupyter Notebook provide a variety of ways to run code. * To run the whole cell, we can click on the play button icon in the cell. * To run only the line our cursor is on, we can use the "Run selection" option from the "Runtime" menu. * To run all cells, we can use "Run all" from the "Runtime" menu. We can also run the whole cell using keyboard shortcuts: * **Shift + Enter:** Runs the whole cell and creates a new one below it. * **Ctrl + Enter:** Runs the whole cell. In addition to code, cells can also contain comments. These are lines that are not executed by the program. Comments are often used to explain what the code does. Comments in Google Colab and Jupyter Notebook start with the hash symbol (#). For example, we could add a comment like this: ```python # Hi, I'm a comment! ``` Anything after the # symbol will not be executed.