Understanding Progressive Enhancement - RooyyDoe/League-of-legends-survey GitHub Wiki
Article by Aaron Gustafson
Progressive enhancement means you make sure the core functionality works, and then you add extra features when the browser can handle these features.
Both graceful degradation and progressive enhancement consider how well a site works in a variety of browsers on a variety of devices
Perspective
Graceful degradation
Older browsers are not the main focus here. They focus on building the website for the most advanced/capable browsers. The testing for older browsers will probably happen at the end of the project and then they will just use small fixes and keep the advanced/capable browsers number one.
Progressive enhancement
Focuses on the content. Content is the reason we create websites every website does something else with content, but all the websites require content. If you want a progressive enhancement mindset you simply think from the content out. The content forms the base on which you layer your style and interactivity on.
Start with your content peanut, marked up in rich, semantic (X)HTML. Coat that content with a layer of rich, creamy CSS. Finally, add JavaScript as the hard candy shell to make a wonderfully tasty treat (and keep it from melting in your hands).
The writer talks a lot about how people can be different and that you need to keep remembering that. They can work with older browsers or have an older telephone that can't handle all the new features that have come out in the years. For this, they need a back-up plan and that is why you need to work from the content.
Also, keep in mind that some people have disabilities that can nuisance the user experience on a browser or mobile device. Maybe they only have one hand that they can use or they can't see. So you need to think about the interaction as well.