We start out with our service by adding a new service class file.
In Craft, a service is defined as the class file where you handle “business logic”. The service classes are attached to the module class as a Yii component. In a refined plugin or module, a service class is how your module or other code can interact with the functionality of the module.
Think about the service class as the programmatic entry point to do something in your module. You want to add CP nav items, you do access a method in the service class to do that. Yes, we do need to register the events in the init() method still but this is a special case.
My First Craft CMS Module is made up of the following videos: