Web 2.0 is a new version of the World Wide Web, where it does not update any technical specifications, but changes in the ways software developers and end-users use the web.
The net or the Internet, host services such as social-networking sites, video sharing sites, wikis, blogs, and folksonomies. Websites who make use of Web 2.0 applications allow it’s users to do things more on the net rather than just retrieving information. The Web 2.0 brings the idea of interconnectivity and interactivity of the web delivered content.
Net sites with Web 2.0 application provides users with rich experience and participation. It usually provides dyanamic content, metadata, web standards and scalability. There is openness, freedom and collective intelligence through users participation.
O’Reilly who coined the word Web 2.0 in 2004 described Web 2.0 into four levels of hierachy:
1. Level 0 – applications that work offline or online. Examples of these net sites are MapQuest, Yahoo Local, and Google Maps.
2. Level 1 – applications that operate offline but may gain features online. Examples of these net sites are Writely, now known as Google Docs & Spreadsheets and iTunes.
3. Level 2 – applications that operate offline but gain advantages from going online. An example is Flickr, as it benefits from its shared photo-database and from its community-generated tag database.
4. Level 3 – application considered to be the most Web 2.0 oriented. It exist only on the net, deriving their effectiveness from the inter-human connections and from the network effects. Examples of these net sites are eBay, Craigslist, Wikipedia, del.icio.us, Skype, dodgeball, and AdSense as examples.