A Design Pattern is a catalogued solution that has been applied and tested in multiple situations to produce well-designed reusable object-oriented software. Designing with reusability is an art, typically acquired after many years of software development, refining and iterating over designed software modules.The design patterns will be described using Intent, Motivation, Sample Code, Applicability, Structure, Consequences and its Known Uses. Focus is on the methodology for developing software systems. The course tackles problems from a business prospective. Methods and techniques for functional requirements analysis and specifications, design, quality assurance, process technology are discussed.