Platform · 1991–now · Web Boom
HTML / CSS
The document layer of the web. Frameworks come and go; tags and stylesheets remain the delivery surface.
HTML/CSS stuck because browsers are the universal client and accessibility, SEO, and progressive enhancement still start here. Frameworks abstract them; they do not replace them. The fad is pretending the DOM is an implementation detail forever.

Context
The browser ate the desktop
The web became the default delivery surface. LAMP and Rails made shipping cheap; Ajax made pages feel like apps; SOAP/SOA tried to enterprise-ify the wire. REST won by being debuggable with curl. This decade invented the modern product cadence — and the habit of treating every new framework as destiny.
Compare with
Related
Platform · 1991–now
HTTP / HTTPS
The application protocol of the internet. HTTP/2 and HTTP/3 are evolutions, not replacements.
Architecture · 2005–now
Ajax SPAs (early)
Partial page updates without full reloads. Became the mental model for every modern front-end framework.
Framework · 2006–2018
jQuery
DOM peace treaty for a fractured browser world. Mission accomplished — then frameworks ate its job.
Framework · 2020–now
Hypermedia / htmx
HTML as the engine of application state — a deliberate counter to SPA maximalism. Peak backlash; now a plateau, not a climb.