Information system modelling/Introductory lesson
Before we start learning how to model using the UML diagrams, it is important to understand a few terms and techniques that are used in modelling information systems.
Information system 
In Leyman's terms, an information system that gets information, processes it and outputs it in a way which is helpful to a business or an individual. A good example of an information system is an ATM. It gets an input from the user, which is processed, and the end result is (usually) money in the hand of the user.