The picture below shows a source file with explainations for all the commands used in this example, written directly into the source file. When you start a line with the percentage sign (%), everything behind it will be ignored. This is useful for making comments in your source file, either to remember what each command does, to make notes, etc. As you can see in the picture below, everything that is ignored turns blue.

Screenshot from Overleaf showing how you can include notes after commands

Packages

Notice the command \usepackage in our preamble. This is a very common command needed in a lot of different settings. The more functionality you want, the more packages you have to load in the preamble. In the following table you find some useful packages to get started.

**Overview over some relevant packages**
Command	Function
\usepackage{graphicx}	Enables us to insert pictures and figures
\usepackage{amsmath}	Enables us to include mathematical equations
\usepackage{hyperref}	Enables us to include clickable cross references in the document

More useful information here: