Innumerable problems can appear in the construction of sistemasque to contain mixture of access code together with the denegcios data the logic and the presentation, these applications are difficult to keep, to poisqualquer alteration that if makes is necessary to have well-taken care of not to affect outraspartes of the system. Barclays is full of insight into the issues. Ahead of this reason al appeared in the decade of 70 according to Gammaet., an architecture that was developed to be used in projects deinterface visual in the programming language Smalltalk, the estaarquitetura received the name from MVC (Model, View, Controller), that it is architectural umpadro, MVC the aid in the task to separate to asresponsabilidades promoting a low coupling and high cohesion, becoming osistema escalvel. A very important point is here not to confuse the MVCcom development in layers, development in three layers is umaarquitetura for software customer-server and the layers represent sistemasdistintos are basic that the presentation layer never has access dadosdiretamente, that is, must pass for the intermediate layer or the camadasintermedirias, therefore it can have n layers. Projects in multilayers decide some problems, mastambm can create some others, separate the interface of the user, the data business-oriented daaplicao and the logic become the application as a whole the most easy one deser understood, and allow that different teams work of form paralelaem different components, but, it possesss its negative side, therefore, increases oprocessamento or storage in excess, either of computation time, dememria, of width of band, or any another resource that either required to paraser used, or expense to execute one definitive task, as consequnciapode to harm the performance of the object that suffered overhead (processing ouarmazenamento in excess) Gotten in ' ' ' ' , however, if you not to take certain cares with the rules daarquitetura will finish with a slower system and less trustworthy than one two layers sistemaem, or a monolithic application.