Progressive enhancement

Progressive enhancement is a strategy for web design that emphasizes core webpage content first. This strategy then progressively adds more nuanced and technically rigorous layers of presentation and features on top of the content as the end-user's browser/internet connection allow. The proposed benefits of this strategy are that it allows everyone to access the basic content and functionality of a web page, using any browser or Internet connection, while also providing an enhanced version of the page to those with more advanced browser software or greater bandwidth.

"Progressive Enhancement" was coined by Steven Champeon at the SXSW Interactive conference on March 11, 2003 in Austin, and through a series of articles for Webmonkey which were published between March and June 2003.

Specific Cascading Style Sheets (CSS) techniques pertaining to flexibility of the page layout accommodating different screen resolutions is the concept associated with Responsive web design approach. .net Magazine chose Progressive Enhancement as #1 on its list of Top Web Design Trends for 2012 (Responsive design was #2). Google has encouraged the adoption of progressive enhancement to help "our systems (and a wider range of browsers) see usable content and basic functionality when certain web design features are not yet supported".

The strategy is an evolution of a previous web design strategy known as graceful degradation, wherein designers would create Web pages for the latest browsers that would also work well in older versions of browser software. Graceful degradation was supposed to allow the page to "degrade", or remain presentable even if certain technologies assumed by the design were not present, without being jarring to the user of such older software. In practice, graceful degradation has been supplanted by an attitude that the end user should "just upgrade".

In Progressive Enhancement (PE) the strategy is deliberately reversed: a basic markup document is created, geared towards the lowest common denominator of browser software functionality, and then the designer adds in functionality or enhancements to the presentation and behavior of the page, using modern technologies such as Cascading Style Sheets or JavaScript (or other advanced technologies, such as Flash or Java applets or Scalable Vector Graphics (SVG), etc.). All such enhancements are externally linked, preventing data unusable by certain browsers from being unnecessarily downloaded.

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