A simple example of an event is that it is raised when a record is modified in Navision. There is, however, especially in ERP systems, a large number of situations where what is called for is a "time-based" event. An example of a time-based event is:
Go through all purchase orders, and send a reminder to the vendor if there is less than six days to the promised receipt date.
Because there is no "timer" in Navision that can be used for this, the way to solve this problem is to create a report, or something similar, that performs this processing, and then run this report at fixed times. This, of course, means that there is an element of manual processing involved, namely running the report, but there are still great gains from using Business Notification in an example such as this. The alternative, fully manual, solution would be to go through such a report manually, and contact each vendor. This would be time-consuming, and also more prone to oversights.
When developing such a solution, there are some things that you need to be aware of. The most important is that you will need to keep track of who has already received a notification. In this example, you would need to track the vendors who have already received a notification, to avoid sending them inappropriate e-mail messages.
Some of the templates that are delivered with Business Notification are time based. If you want to develop something similar you can look at these solutions for inspiration. You can also use the framework that has been used for these solutions. There is also some documentation available in the partner guide for Business Notification.