Rich Internet Applications or RIAs are, as defined by Wikipedia, “web applications that have the features and functionality of traditional desktop applications that typically transfer the processing necessary for the user interface to the web client”. RIAs are characterized by rich user interface interactions such as drag and drop utilities, inline text editing, and page segment updating as well as the use of JavaScripting for client-side or browser-based processing; thereby, limiting the number of server calls required and ultimately speeding up the processing time.

RIAs are all the rage and with good reason. They are programmatically and experientially a cut above the traditional page-based model of the web. Many Web 2.0 companies and sites utilize the dynamism afforded by RIAs such as Yahoo’s featured stories section which is a user-updatable news item previewer and Google Maps which allows users to pan maps. A common usability issue with anything new is that its precisely that—new and different. Users must first learn how the new feature or tool set works and how to use it. I am personally not a big fan of tours and demos—although they are nonetheless necessary, as I, myself, don’t initially use them and in my experience, users tend to want to first take the ‘learn by doing’ approach to figure it out for themselves. Its a great test of the intuitiveness of an interface. So, ensuring that the visual cues and signals are clear and distinct is critical to the UX success of your RIA especially given the richness and sometimes complexity of the interactivity being afforded.

Here is a great resource to learn more about RIAs and their usability: http://www.uie.com/browse/ria/.