I wrote this a few years ago…
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There is a lot of talk about flash websites, and much of it is just plain wrong. As with any technology, there are advantages and disadvantages. Flash is a browser plugin, it offers extended features than the normal browser. Flash is pre-installed on most laptops and desktop machines and is a free download. According to Adobe, it is installed on 98% of computers, but this does not figure into mobile devices and tablets…
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UPDATE ON 1/28/15
Google just announced YouTube now defaults to HTML5 video as standard in Chrome, Internet Explorer 11, Safari 8, and in beta versions of Firefox. The time has come to ditch the aging Flash in favor of HTML5. It looks like another hatchet to bury flash. In the short term, Flash video looks prepared to survive with online advertising, smaller video sites, and YouTube visitors who aren’t using a modern browser. I just hope the tools and techniques for HTML5 accelerate so that we can see some more inspiring websites.