⟩ How to name your module?
The first step in creating a module is to choose a "short name" for it. This short name will be used in all file and function names in your module, so it must start with a letter and by Drupal convention it must contain only lower-case letters and underscores. For this example, we'll choose "onthisdate" as the short name. Important note: It is not just a convention that the short name is used for both the module's file name and as a function prefix. When you implement Drupal "hooks" (see later portions of tutorial), Drupal will only recognize your hook implementation functions if they have the same function name prefix as the name of the module file.
It's also important to make sure your module does not have the same short name as any theme you will be using on the site.