Web 2.0 is the new World Wide Web. In it, you can do a lot more than the old Web. You can now interact on websites in addition to viewing static data. Web 2.0 web sites that use technology beyond the static pages of earlier web sites. The term was coined in 1999 by Darcy DiNucci and was popularized by Tim O'Reilly at the O'Reilly Media Web 2.0 conference in late 2004. Although Web 2.0 suggests a new version of the World Wide Web, it does not refer to an update to any technical specification, but rather to cumulative changes in the way web pages are made and used.
A Web 2.0 site 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 websites where people are limited to the passive viewing of content. Examples of Web 2.0 include social networking sites, blogs, wikis, folksonomies, video sharing sites like YouTube, hosted services, web applications like Office, and mashups. You can create and edit any of these types of websites.
The client-side (web browser) technologies used in Web 2.0 development include Ajax and JavaScript frameworks such as jQuery, Ext JS and Prototype JavaScript Framework. Ajax programming uses JavaScript to upload and download new data from the web server without undergoing a full page reload.
To allow users to continue to interact with the page, communications such as data requests going to the server are separated from data coming back to the page. Otherwise, you would have to routinely wait for the data to come back before they can do anything else on that page, just as a user has to wait for a page to complete the reload. Your site will get much higher performance because it doesn't have to refresh.
Data are transmitted and received via Ajax, which means only parts of a webpage will be refreshed when a request for information is made and new information is delivered. This means that your website can work like any program on your computer if you get someone to build a site that has rich functionality.
On the server side, Web 2.0 uses many of the same technologies as Web 1.0. Languages such as PHP, Ruby, Perl, Python, as well as JSP, and ASP.NET, are used by developers to output data dynamically using information from files and databases. What has begun to change in Web 2.0 is the way this data is formatted. In the early days of the Internet, there was little need for different websites to communicate with each other and share data. In the new "participatory web", however, sharing data between sites has become an essential capability. To share its data with other sites, a website must be able to generate output in machine-readable formats such as XML (Atom, RSS, etc.) and JSON.
Stuff like comments, order information in a shopping site are all stored in databases online. They are readily accessible so you can retrieve them any time. Information storage is a big differentiator between Web 1.0 and 2.0 websites.
With Web 2.0 technologies, you can do a lot more that ever before. You can capture people's data and make your own analysis when people indirectly enter their information into your databases. You can use the information to target advertising. The server side languages allow you to add interactivity, dynamically display web pages, and store entered information into databases. JavaScript lets you make fancy effects in your pages. Ajax lets you get and set information instantly in your website.
