Refactoring

Refactoring is the process of changing a software system in such a way that it dose not alter the external behaviour of the code yet improves its internal structure. It is a disciplined way to clean up code that minimizes the chances of introducing bugs. In essence when you refactor you are improving the design of the code after it has been written.

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Software developers are professionals. Our job is to build effective software as rapidly as we can.
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A schedule-driven manager wants me to do things the fastest way I can; how I do it is my business. The fastest way is to refactor; therefore I refactor.

-- Refactoring - Improving the design of existing code. Martin Fowler