A Closer Look: Definition of Graceful Degradation

Graceful degradation refers to the process of designing something so that if an error occurs in part of the design, the system as a whole will still work properly. While graceful degredation is used most often in computer vocabulary today, the concept has been around since long before the computer age. Graceful degredation is used most often in mission critical or life-critical systems. Places where a machine or process must continue without interruption often incorporate multiple redundant systems of graceful degredation that can handle the process when a fault occurs.

The field of web design is heavily dependent upon and regularly uses graceful degredation to ensure that websites display properly. As World Wide Web browsers continue to incorporate new features and enhancements, older browsers may have difficulty working with the HTML coding of web pages. This problem will only worsen as time goes on. When HTML changes, CSS 3.0 comes online and browsers begin to offer bigger and better features, more and more websites will fail to work properly unless the code is written in such a way as to still work with browsers that have lower capabilities. The design of webpage code that can display content regardless of the browser’s capabilities is a form of graceful degradation. To illustrate what this means in practice look at an example using the tag that is very common in HTML coded pages. One of the earliest browsers was Lynx. It was strictly text based. Comparing a modern browser like Firefox with Lynx when it comes to their ability to display an HTML page that contains a graphic image, is like comparing apples and oranges.

If the page is written for today's browsers, as most pages are, Lynx will fail to be able to process the page code. The HTML code is a newer tag in HTML than was available in the time where Lynx was a very popular browser. Firefox would display the page as it was intended to be viewed, but without graceful degredation, Lynx would not. If the page was written in code that was designed to be able to handle browsers of more limited functionality, at the point in the code that required the image to be displayed a text description of the image would be displayed and the rest of the page would then display as was intended. This is graceful degredation in action. Changing the coding of HTML pages to accommodate browsers of lower functionality takes both forethought and planning. The goal of most websites is to convey information to other viewers and in order to be successful at that task, provisions must be made for a large variety of hardware and software.

Certainly being able to use all the bells and whistles that are available in the current browsers makes the page look enjoyable, and it also let’s the designer display lots of special characteristics and features to convey his message. However, designers must remember that the basic goal of the webpage is to convey your message to the viewer. Therefore, every page should be written such that the message is communicated even if one or more of the bells and whistles fail to work or function properly. HTML, from the beginning, was designed to be forward thinking and expandable. By instituting graceful degradation at the onset, as the language evolved and changed, browsers would still be able to display content in any form from very basic to the most advanced mechanism available. If you look back at the example we discussed earlier, the tag in HTML can display a number of graphic files on the webpage. But for computers and browsers that don’t support graphics, there is a parameter in the syntax of the tag that displays a textual description of the image that would have been displayed. By substituting a string of text at the location of the image on the webpage, the general message of the webpage is conveyed in textual form in a way that is equivalent to the more pleasing and visually appealing page that is produced in a browser that supports graphics. Properly written web pages using HTML conventions will in general be able to support graceful degradation. Pages that don’t fall into this category may have to be rewritten in such a way as to provide that support if the page is deemed critical to the site goal.