The technology infrastructure of Web 2.0 is complex and evolving, but includes server software, content syndication, messaging protocols, standards-based browsers, and various client applications. (Non-standard browser plugins and enhancements are generally eschewed.) These differing but complementary approaches provide Web 2.0 with information storage, creation, and dissemination capabilities that go beyond what was formerly expected of websites.
A website could be said to be built using Web 2.0 technologies if it featured a number of the following techniques:
Technical:
CSS, semantically valid XHTML markup, and Microformats
Unobtrusive Rich Application techniques (such as Ajax)
Java Web Start
Flex/Laszlo/Flash
XUL
Syndication of data in RSS/Atom
Aggregation of RSS/Atom data
Clean and meaningful URLs
Support posting to a weblog
REST or XML Webservice APIs
Some social networking aspects
General:
The site should not act as a “walled garden” – it should be easy to get data in and out of the system.
Users should own their own data on the site
Purely Web based – most successful Web 2.0 sites can be used almost entirely through the browser
Applicable to an emerging generation of game development, proposed as Thin games