Modeling is simplification of realities.
2. Why Modeling?
2.1 Help us make a system visual According to the realities.
2.2 Modeling allow us to describe the system's architechture and procedure in detail.
2.3 Modeling give a template to consturct a system.
2.4 Modeling give documents for our system.
Modeling make complex sysyem into a lot of simple ones which are easy to work out one by one.
3. At OOP system uses a serial diagrams including use case diagram, design diagram, process diagram, implement diagram and deployment diagram.