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To understand graceful degradation, it is very important to understand first Tag Degradation. Tag degradation is a phenomenon which describes the incompatibilities which could be either deliberate or accidental, in the web documents. All the web browsers follow one simple rule with respect to HTML tags which states that, “If you do not understand a tag, just ignore it.” Whenever a web browser encounters any tag and it fails to understand and display it, the result is degradation. This is where the concept of graceful degradation comes in. Graceful degradation is a simple but a powerful technique which ensures that a web page should be coded in such a way that just in case if the browser is not able to cope up with any of its effect or feature the page should yet be displayed in a simplified form.

When the degradation takes place, the content of your page will be either lost to the web browser or the content of your page will still be completely accessible, which will depend solely on whether the degradation is graceful or not. As we all know that HTML is continuously changing and different browser have different characteristics and each one supports different elements, therefore graceful degradation is the main element which ensures that all the pages are readable and accessible in all the browsers. The standards for HTML have been written keeping this important key i.e. graceful degradation in mind.

Graceful degradation has two basic rules. Firstly any browser should be able to view the content of the site and secondly any browser should be able to navigate the site. This simply indicates that the website should still be able to operate even when it is being viewed with less optimal software which does not support any kind of advanced features. You can add as many special effects as desired but always ensure that the site is very much operative and usable without them as well. The essence of quality web programming is ensuring graceful degradation. By definition, we all know that no HTML will run on all the browsers, errors are inevitable. Although a page might appear different in an older version of the browser in comparison to the latest ones but what is important is the fact that information should always be available to the user.

There are various good examples which can successfully describe graceful degradation, such as the use ALT attribute in IMG tags. By using alt, we are providing a text alternative to the browser. In case the browser is not able to display the image it can provide the relevant text information. Another example can be if CSS is used to describe the text color, and in case if the web browser does not support the style sheets the text will return to its default color which is black and thereby making the text readable by the user. Graceful degradation is only possible if the HTML used in the web pages should be valid which means that it should be grammatically correct. Browser should have something to fall back on. When the HTML is written badly, it would mean that when the browser tries to ignore certain parts which are not understandable, atleast the content can be displayed. And finally the tag should be closed at the end. If the tag is left open, it would completely fail.