Progressive Enhancement vs. Gracefully Degradation

Currently in the web development world, there are two different strategies for dealing with development against different browsers or systems. One is Progressive Enhancement and one is Gracefully Degradation.

The first one is you first build a base website that all the browser can render, then enhance the features that newer browser support.  So the experience or look and feel will be slightly different for those people who use new browser and for those that use older ones. It is a bottom-top design - you first design the base and build special features on top for modern browsers. And the benefit is that it contains all the information (contents) a user needs.

The second one, on the other hand, it is a top-bottom design and it prioritize presentation. You first start with the modern browsers, and later you fix the older browsers such that it doesn't break.

Below is I copied from other articles I read before :

Graceful Degradation is a widely used term which ideology is basically using the latest technologies first, and then fix anything that needs fixing for older browsers. We do this on a daily basis: most of us code for Firefox first, then fix Internet Explorer. That is Graceful Degradation in the practice.

Progressive Enhancement refers to the habit of building first for the less capable, outdated browser and then enhance for the latest technologies. We, too, use this on a daily basis. For example, most of the times we code a website we start with the markup and then apply an external CSS file where we add all the styling. That is Progressive Enhancement in the practice.

YUI Graded Browser Support has mentioned the following:-

"These two concepts influence decision-making about browser support. Because they reflect different priorities, they frame the support discussion differently. Graceful degradation prioritizes presentation, and permits less widely-used browsers to receive less (and give less to the user). Progressive enhancement puts content at the center, and allows most browsers to receive more (and show more to the user). While close in meaning, progressive enhancement is a healthier and more forward-looking approach. Progressive enhancement is a core concept of Graded Browser Support."

For more information, I found these two links quite comprehensive:

http://dev.opera.com/articles/view/graceful-degradation-progressive-enhance/

http://www.thatagency.com/design-studio-blog/2009/07/progressive-enhancement-vs-graceful-degradation/