The Requirement Engineering (RE) is the most important phase of the Software Development Life Cycle (SDLC). This phase is used to translate the imprecise, incomplete needs and wishes of the potential users of software into complete, precise and formal specifications. The specifications act as the contract between the software users and the developers. Therefore the importance of Requirement Engineering is enormous to develop effective software and in reducing software errors at the early stage of the development of software. Since Requirement Engineering (RE) has great role in different stages of the SDLC, its consideration in software development is crucial. There exist a number of approaches for requirement engineering.