Web 2.0 - refers to World Wide Web websites that emphasize user-generated content, usability (ease of use, even by non-experts), participatory culture and interoperability (this means that a website can work well with other products, systems, and devices) for end users. The term was invented by Darcy DiNucci in 1999 and popularized several years later by Tim O'Reilly and Dale Dougherty at the O'Reilly Media Web 2.0 Conference in late 2004 Web 2.0 does not refer to an update to any technical specification, but to changes in the way Web pages are designed and used. The transition was progressive and there is no precise date on which the change occurred. Web 2.0 also called Participative and Social Web.
A Web 2.0 website may allow users to interact and collaborate with each other in a social media dialogue as creators of user-generated content in a virtual community, in contrast to the first generation of Web 1.0-era websites where people were limited to the passive viewing of content. Examples of Web 2.0 features include social networking sites and social media sites (e.g., Facebook), blogs, wikis, folksonomies ("tagging" keywords on websites and links), video sharing sites (e.g., YouTube), hosted services, Web applications ("apps"), collaborative consumption platforms, and mashup applications.
Whether Web 2.0 is substantively different from prior Web technologies has been challenged by World Wide Web inventor Tim Berners-Lee, who describes the term as jargon. His original vision of the Web was "a collaborative medium, a place where we [could] all meet and read and write." On the other hand, the term Semantic Web (sometimes referred to as Web 3.0) was coined by Berners-Lee to refer to a web of content where the meaning can be processed by machines.