The Web is both a hypertext system we navigate to find information and a software application we use to accomplish tasks. As a hypertext system, the Web does an adequate job, with enough built-in functionality to allow for describing and connecting documents and for providing document access. As a software application, the Web is less well equipped.
The Web is a client-server application that does not support page-level interactivity. Web interactions are based on a dialog between the Web browser (client) and the Web server (server). The browser requests a page; the server delivers it. Once the page is delivered, the dialog is suspended until the browser makes another page request. In the Web environment, the only way a user can interact with a page is by clicking on a link or submitting a Web form, which prompts the browser to reopen its dialog with the server. In fact, links and forms are the Web’s only native modes of interactivity. Links allow users to navigate within and among documents; forms collect information from users. As such, the Web cannot provide the level of interactivity that we have come to expect from desktop and CD-ROM applications.
Some sites use scripts, Java applets, ActiveX, and plugins (such as Flash or QuickTime) to provide a higher degree of interactivity than can be provided using standard Web structures. Unfortunately, equitable and universal access is difficult to provide when essential site content is designed using nonstandard formats.
Generally, the Web is most accessible when sites are built to standards. However, some sites require functionality that cannot be accomplished using standard Web coding. In these cases, apply the universal usability guidelines to the greatest extent possible, and provide alternate access for users who cannot access the nonstandard content.