Web 2.0 refers to websites that allow users to interact with each other and change website content, unlike earlier websites that only allowed passive viewing of information. Examples include social media sites, blogs, wikis, video sharing, and applications that combine data from multiple sources. Key features include user-generated content through searching, linking, tagging, and authoring content. Popular social media platforms associated with Web 2.0 include Facebook for connecting with friends, Twitter for sharing what's happening now, Flickr for photo sharing, and LinkedIn for professional networking.

1. WEB 2.0 By J.Radhakrishnan P.Ramesh

2. Definition of Web 2.0? The term "Web 2.0" (2004–present) is commonly associated with web applications that facilitate interactive information sharing, interoperability, user-centered design, and collaboration on the World Wide Web

3. A Web 2.0 site allows its users to interact with other users or to change website content, in contrast to non-interactive websites where users are limited to the passive viewing of information that is provided to them.

4. Examples:- Hosted services, web applications, social-networking sites, video-sharing sites, wikis, blogs, mashups, and folksonomies.

5. Technology Web 2.0 draws together the capabilities of client- and server-side software, content syndication and the use of network protocols. Standards-oriented web browsers may use plug-ins and software extensions to handle the content and the user interactions. Web 2.0 sites provide users with information storage, creation, and dissemination capabilities that were not possible in the environment now known as "Web 1.0".

6. Features and Techniques:- Search

7. Finding information through keyword search.

8. Links

9. Connects information together into a meaningful information ecosystem using the model of the Web, and provides low-barrier social tools.

10. Authoring

11. The ability to create and update content leads to the collaborative work of many rather than just a few web authors. In wikis, users may extend, undo and redo each other's work. In blogs, posts and the comments of individuals build up over time.

12. Tags

13. Categorization of content by users adding "tags" - short, usually one-word descriptions = to facilitate searching, without dependence on pre-made categories. Collections of tags created by many users within a single system may be referred to as "folksonomies"