Progressive enhancement is a strategy for web design that emphasizes accessibility, semantic markup, and external stylesheet and scripting technologies.
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Progressive enhancement is the mostly used strategy in web design. It let us buildup a solid foundation for maximum accessibility, and then slowly add features on top of that, meanwhile ensure the basic functions are still working perfectly. The opposite method is called graceful degradation.
This collection of articles will help you build up some fundamental ideas and help you improve on your web projects. Enjoy!