"Web 2.0" was the modern web around 2008, and concurrent with or associated with things like AJAX and Ruby-on-Rails - here is an old article expanding on the term:

https://www.informit.com/articles/article.aspx?p=1310178

"Web 2.0 is a term (or rather buzzword) that you often hear when describing most “modern” web sites; however, it shouldn’t be a new concept to web developers. Web 2.0 is actually a consolidation of many existing technologies that allows you to provide a rich interactive user experience over the web. Examples of Web 2.0 technologies include, but aren’t limited to, the following areas:

  - Rich Internet Applications (RIAs), which include AJAX, Adobe Flash, Silverlight, and Moonlight
  - Web services
  - Blogs
  - Wikis
  - Social networking
  - Social bookmarking
  - RSS/Atom"

Just a reminder on how easy it is not seeing the forest because of the trees, and instead focusing on things that are shiny and noisy yet will not last.

What lasted was to move from server-side computing where all the UI was rendered server side as HTML pages, to a world where a lot of the computing and all of the UI rendering was done client-side.

So it meaningful to ask: Are we going into a world where the centralised server gets even less of a role because of things like data storage, payments, authentication are done in a distributed manner or purely client-side?