Based on your UI requirements, you can make a decision on the type of UI for your application. There are a number of different UI types, each with their own strengths and weaknesses. Often, you will find that your UI requirements can be fulfilled with more than one UI type. It is also possible that no single UI type completely covers all of your UI requirements. In this case, consider creating different UI types on top of a shared set of business logic. An example is creating a call center application where you want to expose some of the capabilities for customer self help on the Web and on mobile devices.

Mobile applications can be developed as thin client or rich client applications. Rich client mobile applications can support disconnected or occasionally connected scenarios. Web or thin client mobile applications support connected scenarios only. Device resources may also prove to be a constraint when designing mobile applications.

Rich client applications are usually stand-alone or networked applications with a graphical user interface that display data using a range of controls, and are deployed to a desktop or laptop computer for use by a local user. They are suitable for disconnected and occasionally connected scenarios because the application runs on the client machine. A rich client UI is a good choice when the UI must support rich functionality and rich user interaction or provide a highly dynamic and responsive user experience; or when the application must work in both connected and disconnected scenarios, take advantage of local system resources on the client machine, or integrate with other applications on that machine.

Rich Internet applications (RIAs) are usually Web applications with a rich graphical user interface that run inside a browser. RIAs are typically used for connected scenarios. A RIA is a good choice when your UI must support a dynamic and responsive user experience or use streaming media, and be widely accessible on a range of devices and platforms. They can take advantage of the processing power of the client computer, but cannot easily interact with other local system resources such as webcams, or with other client applications such as Microsoft Office.

Web applications support connected scenarios and can support many different browsers running on a range of operating systems and platforms. A Web UI is a good choice when your UI must be standards-based, accessible on the widest range of devices and platforms, and work only in a connected scenario. Web applications are also well suited to applications whose content is to searchable by Web search engines.

Console-based applications offer an alternative text only user experience, and typically run within command shells such as a Command window or Power Shell. They are most suitable for administrative or development tasks, and are unlikely to be part of a layered application design.