We’re all familiar with the ideas of backwards compatibility and graceful degradation. Now it’s time to embrace the idea of progressive enhancement.

Like backwards compatibility and graceful degradation, progressive enhancement is not a new idea. At its simplest, progressive enhancement means that a system will provide a base level of performance, with higher performance provided for clients which can handle it. But the base level of performance must be such that it provides everything necessary to achieve the goals of the system.

For the web, progressive enhancement means providing a basic level of content for everyone, even the most primitive browsers, and then adding in more content (like multimedia) and capabilities (like fancy Flash navigation or form auto-complete) for those who want it and have the resources for it.

Progressive enhancement is surprisingly easy to apply to web projects. The industry best practices of semantic markup and separation of presentation from content provide a great foundation, and from there you can apply some simple techniques to progressively enhance that base. AJAX techniques, for example, are excellent choices for progressive enhancement, though it’s very important not to rely on AJAX as the sole provider of necessary function.

The biggest myth about progressive enhancement is that it severely constrains design and creativity, requiring a sort of “least common denominator” approach to producing websites. This couldn’t be farther from the truth. With a solid foundation of semantic markup and standards compliance, it’s easy to use progressive enhancement to create amazing websites with rich interaction and multimedia capabilities.

The benefits of progressive enhancement come directly from the basic level of content it provides, which is aimed at everyone. Progressive enhancement assures that even simple user agents can access your content and parse it correctly, which assures accurate search engine placement as well as a basic level of accessibility. And you’re still providing a top-notch interactive experience for the majority of users who have modern browsers and the resources to handle it.

- Jon Reid, Interface Development