Area is a MVC folder. You can add multiple area in one project. Each area can have: model, view and controller

Areas are logical grouping of Controller, Models and Views and other related folders for a module in MVC applications. By convention, a top Areas folder can contain multiple areas. Using areas, we can write more maintainable code for an application cleanly separated according to the modules.

For large application where we need to have many controllers and associated views it is a good practice to organize the controller and views by creating Area.

In a large Application handling is very easy

Areas Provides the Logical separation of the Model, View and Controller components. For example, we may have individual area for each module in the application.

http://stackoverflow.com/questions/9235030/when-we-use-areas-where-routing-should-be-placed-asp-mvc