if you need to integrate NAV with external system or if you need to generate notifications you can use Events.
I’ve worked on Events when it comes to Extensions concept where in, you will create a NAVApp (which can be used to update the customizations in other systems) and publish the NAVApp. This NAVAPP can be used in any other systems just by installing the App through powershell script.
To create the NAVApp, we need to handle some customized code through events and subscribers by creating a new codeunit.
You can refer the below link to understand in general.