JSF technology is a framework for developing, building server side User Interface Components and using them in a web application.JSF technology is based on the Model View Controller (MVC) architecture for separating logic from presentation.
MVC Design Pattern in JSF
MVC design pattern designs an application using three separate modules:
Purpose of MVC design pattern is to separate model and presentation to enable developers to set focus on their core skills and collaborate more clearly.
Web Designers have to concentrate only on view layer rather than model and controller layer. Developers can change the code for model and typically need not to change view layer.Controllers are used to process user actions. In this process layer model and views may be changed.