Software Engineering is a systematic approach to develop software. For developing Software, one has to have the knowledge of analysis, estimation, prototyping, planning, designing, testing and so on. Software Engineering includes: - Requirement analysis - Human factors - Functional specification - Software architecture - Design methods - Programming for reliability - Programming for maintainability - Team programming methods - Testing methods - Configuration management Software Engineering is the study and application of Engineering to design, development and maintenance of Software. The specification is a document that describes the behavior of the software system to be built. It contains the requirements model and domain model. The requirements model includes the functional and non-functional requirements. Functional requirements are also called capabilities. Non-functional requirements are also called constraints. Non-functional requirements include usability, comfort, security, user friendliness, reliability, performance of Software to the customer.