What is Restructuring: The transformation from one structure to another at the same relative level of abstraction

This chapter presents all the concepts, techniques, and analyses in relation to the problem of reengineering existing (legacy) systems towards new technologies. Reengineering is a sub-problem of software engineering. It is the study and analysis of an existing system for purposes of understanding, maintenance, or migration towards new technologies that arise from day to day, without rewriting the software from scratch. This will save us time and money in the software development process. Author's objective is not to create new terms, but to introduce the terms already in use with new perspectives. So in this chapter, definitions and techniques are introduced, taxonomies and models are proposed, relevant questions are answered, some specialized conferences and journals are listed and compared; all this to highlight the ways to authors who are interested in writing research papers or surveys in the software reengineering field.