I wont give a detailed explication, But I can resume by saying that a Web 2.0 is a Social Web witch make the users able to discuss with the site contains & with each other . You can for example publish articles & the others can read them easily & get Socialize with you . This Technology contains Blogs, Wiki, Social Sites ... It's using Ajax, php, Css for design . Hope, you get what is it !
Web 2.0 refers to web that facilitates interactive information. There's a lot example of Web 2.0 like web-based communities, web apps, social-networking, video-sharing sites, wikis, blogs etc.
Here is an explanation - So what is Web 2.0? Simply put, Web 2.0 is a perceived transition of the web to web applications. Web 2.0 is the next generation of technology solutions where interactive content is the norm. There is no agreement on exactly what Web 2.0 means, depending on who you are speaking with, you may receive different explanations. At it's heart, Web 2.0 is about the maturity of the Web and businesses that are thriving online. While many refer to Web 2.0 as companies that employ powerful web technologies, the key components of the new web are said to include: the web as a platform, collaboration, and syndication. http://www.small-business-software.net/what-is-web-2.htm
Today I'm going to talk about what is Web 2.0. A lot of people ask me what Web 2.0 is. They've heard of things like blogging, they've heard of mash-ups, they've heard of Ajax and other buzzwords, but they don't quite understand what it actually means. They've used Web 2.0 applications such as YouTube, Flicker, a lot of the Yahoo sites, but still there is something missing in explanation. The first part of Web 2.0 is RIA, or rich internet applications. Some buzzwords that relate to that are Flash and Ajax. What rich internet applications really are is how do we bring the experience from the desktop into the browser, whether it's from a graphical point of view or from usability point of view, such as drag and drop, which everyone is used to from the desktop. The second piece of Web 2.0 is SOA. SOA are service oriented architectures. It's one of the key pieces in Web 2.0. That includes buzzwords such as feeds, RSS, web services and everyone's heard of mash-ups. What SOA is all about is how do Web 2.0 applications expose their ality so that other applications can leverage and integrate the ality, providing a much richer set of applications, including the infamous mash-ups. The third piece of Web 2.0 is the social web. Web 2.0 applications tend to interact much more with the end-user. The end-user is not only a user of the application, but is a participant, whether it's by tagging the content, whether he's contributing to the wiki, or doing podcasts or blogging. Part of the social nature of these applications, the end-user is an integral part of the data of the application, providing feedback, allowing the application to leverage the users that are using it. There are really three things you should be looking for in a technology. The first one is that they have very good Ajax support. Ajax is a set of key technologies used to build Web 2.0 applications. It is used to create the rich user experience and it works in any browser, whether Firefox or Internet Explorer. The second thing you should be looking for is a language with very good web services support. As I mentioned before, web services is a key part of Web 2.0 and you need a language that makes it very, very easy to leverage those services. The third is have a language that is iterative. What that means is that you can very easily add features, deploy new features and get those applications updated. It's critical when these web applications are being used by so many end-users and you have to constantly update them.
for me, web 2.0, can describe it more interactive and can become 2ways communication, such as FB, Tweet, myspc and so on. he