Platform · 1996–2020 · Web Boom
Adobe Flash
Animations, games, and video in a plugin the web learned to hate. Steve Jobs wrote the obituary; HTML5 dug the grave.
Why Adobe Flash faded
Flash failed because it was a proprietary runtime with security holes, not part of the open web stack. Mobile never adopted it; advertisers and devs were the last holdouts. HTML5 video and Canvas absorbed the use cases without a plugin tax.
Case studies
Patterns

Compare with
Related
Framework · 2007–2013
Silverlight
.NET in the browser via plugin. Netflix used it; the web moved on anyway.
$ Enterprises built internal dashboards and streaming pilots on Silverlight just as HTML5 and iOS said no to plugins. Migration projects burned budgets Flash already warned them about.
Language · 1995–now
JavaScript
The only language that runs in every browser. Accidental monopoly turned deliberate platform.
Framework · 2006–2018
jQuery
DOM peace treaty for a fractured browser world. Mission accomplished — then frameworks ate its job.