A software development methodology refers to the framework that is used to structure, plan, and control the process of developing an information system. A wide variety of such frameworks have evolved over the years, each with its own recognized strengths and weaknesses. One system development methodology is not necessarily suitable for use by all projects.
These frameworks are often bound to some kind of organization, which further develops, supports the use, and promotes the methodology. The methodology is often documented in some kind of formal documentation.
Vdevture work on the best combination of all available methodologies: Rational Unified Process (RUP) , Agile Unified Process (AUP) & Integrated Methodology (IM) is best suited to specific kinds of projects, based on various technical, organizational, project and team considerations.