In this paper we will discuss the importance of software re-engineering and the reasons behind this importance followed by a discussion on each of these reasons with examples to prove that the re-engineering process is a useful tool to convert old, obsolete systems to more efficient, streamlined systems. And the re-engineering is used to increase maintainability, interoperability, performance and testability. Also re-engineering is used to decrease personal dependency.
Key words: Software Engineering, Software Re-engineering, restructuring, legacy systems