Coupling, is one of the most important programming problems programmers face. Numerous birth of programming techniques its purpose is to decouple the program. For example, object-oriented multi-state, solve the problem of the function of specific needs and achieve tight coupling. MVC framework model solves the problem of tight coupling with the data view. Factory design pattern to solve the problem of functional users and providers of tightly coupled functions. MQ request and reply to solve the problem of tight coupling.
Originally coupled mechanically and electrically art concepts, used to describe a plurality of components or elements interact, with the balance each other. For example the drive shaft is coupled with the gear, the coupling circuit amplifying and filtering circuits. In the engineering field, is coupled weapon, it is a multi-component, multi-module, the main way of mutual cooperation between multiple systems. Coupling in the field of software engineering and has shown a field of different characteristics, in addition to the benefits it brings collaboration, coupling the most important feature is difficult to modify. Few things engineering existing modified and reconstructed, multi-way replacement, the output of new products iteration, the coupling is not a problem in the field of engineering. And software, is a direct product of thinking, not out of something other than the human mind can output software (at least for now), meaning that you can not find fault with it in front of a machine you expect it will need software produced . So the way every time a new product manufactured by a similar iterative software engineering field that is not feasible. Software therefore faced with the situation constantly modified and reconstructed based on the original. At this time, the coupling becomes a big fatal flaw that causes changes every time you have indeed affect the systemic effects. And when you go beyond a complex body's own ability to understand in the face, and can not effectively control the associated change this decoupling has become a major core issues in the field of software.