What is Web 2.0

We hear the term Web 2.0 being thrown around so much these days. What is this Web 2.0? Is it a technology; is it an architecture or features? Well, I think we should visualize Web 2.0 as a set of principles and practices. It is basically a collection of principles that successful business of the current world have applied. Some of the practices and principles of Web 2.0 are -

Treating the web as a platform:
Web services, deliver the software as a service, not as a product
no releases, just continuous improvement
no licensing or sale, just usage
leveraging customer self service
reaching out to all the corners of the web not just the big few
service automatically gets better the more people use it
Harnessing Collective Intelligence:
use of tags - collaborative categorization (folksonomy)
effects of user contributions (users add value and get other users)
Infoware not software:
own certain classes of core data
continuous maintenance of data
treat users as co-developers
Lightweight programming models:
loosely coupled systems
think syndication, not coordination
design for hackability and remixability
Design software for multiple devices:
software written above the level of a single device
Rich user experiences:
rich user experience delivered over the web