410 Part II: Developing an Ajax Library^
The actual content itself in a site or application ranges from static content presented to
all users, to customized content on a per user or group basis, and even to interactive or
participatory content.Continuing along these lines, is our Web application interface a traditional read—that is,
a read and click or form-fill affair—or a direct manipulation interface where objects are
selected, dragged, and combined?Now that we have seen some of the vast range of decisions, we reiterate that progressive
enhancement is the idea of adding features and technologies to a site that corresponds to
increased capabilities of visiting end users. Similarly, the idea of graceful degradation is that
you start with a technically sophisticated and feature-rich site and degrade to the capabilities
and features the user is capable of handling. Both ideas are quite similar to adapting to the
conditions of the user. In the case of progressive enhancement, we build up from basic
features to more advanced, while in the case of graceful degradation, we tend to start with
a high fidelity execution and reduce down.
The choice of starting from basic features and adding on or starting with the desired high-
end experience and seeing what can fall away is somewhat a philosophical one and tends to
be based upon your desire to be inclusive or exclusive. However, regardless of the selection,
there will be different experiences for end users and the reality is that it is not possible to
service everyone with the same experience in an acceptable manner. Ajax developers won’t