What is Web 2.0 ?

what defines a web site as being " web2.0" ? there are many opinions on this , making it difficult to pinpoint an exact definition ; however , some of the features typically associated with web 2.0 sites as follows :

* Using standards-compliant HTML and CSS . This allows sites to work across many plat-form and helps with accessibility .
* Using Ajax to provide a rich user interface . By performing trivial operations in the background using XMLHttpRequest , web Pages can be nore functional and intuitive .
*Sharing Data using feeds and web services . users like to aggregate many feeds to easily receive content update from their favorite sites using web feeds . Additionally , web services can enable one site to use data from other sites .
*Incorporating social networking tools . Blogs and forum can enable users to communicate with each other.

While none of these features or aspects of development are new , we use the Web 2.0 term to describe the current generation of web sites that make good use HTML and CSS while perhaps improving their interface with Ajax and social-networking tools .