An information system is a system that manages information and data critical to the business organization or any other corporate. In the modern computerized world, almost all the organizational activities revolve around computerized information system. Such system need to be able to fulfill all the information needs of the organization in a continued manner. Since the type, nature, importance and usability of the information and its delivery mechanism changes with time, the system that manages and delivers information needs also to be flexible to absorb all or most of those changes. Otherwise, the information system itself becomes less and less useful, finally becoming obsolete and replaced a new system. However, replacing existing system with the new one needs a lot of investment and effort. So, to avoid this, the information system must be designed and developed with a lot of foresight and planning so that it is flexible enough to absorb necessary changes and prolong its own viability for the organization. This saves money, ensures long continuation and avoids unnecessary effort to change systems frequently.