> I thought "web 2.0" came hand in hand with the adoption of AJAX for requests and dynamic updates within a single page? The WWW was full of user-generated content long before then.
AJAX dates back to 1998 (1997?) though it was an IE-only proprietary feature for years until Firefox added it (Netscape might have had it too) in the early 2000s.
> Reading through the article that you linked, as well as following some others from there, it looks like a little bit of retconning.
In my experience, "Web 2.0" was a non-technical definition: it was always about "user-generated content" that had minimal human curation (think: Digg.com). Arguably this should also include vBulletin/phpBB-style web-forums, Coppermine-style online photo galleries, PHPNuke-style content-management and portal systems, and so on... - however those kinds of web-applications all date-back to the 1990s so they were hardly new. Instead, for Web 2.0 people moved from self-hosted forums to central-hosted link-aggregation ("social bookmarking") sites like Reddit and Delicious.
Now that I try to re-remember, I recall how "Web 2.0" was not just "user-generated content" but also all about "the social web". MySpace was Web 2.0, as was Facebook (this was the early days when Facebook was criticized for not allowing their users the same latitude in restyling their profile page as they could on MySpace... funny that).
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Anyway, despite AJAX's use since the late-1990s in Microsoft OWA, it was definitely being used in the early-2000s in the wider web (2001-2005) prior to "Web 2.0" being a thing. We were using Mootools instead of jQuery back then. I remember it took Microsoft until late 2005 to natively support low-code AJAX requests in ASP.NET WebForms ("ASP.NET AJAX"), prior to that doing AJAX requests needed a lot of hand-written JS code, which back then was super unreliable (this was before browsers even had Developer Tools windows and built-in script debuggers: we all were using the Microsoft Script Debugger and Visual InterDev to attach to IE/MSHTML's JS engine's debugging functionality.