As web 3.0 is the emerging trend in today’s world so i want to know what are the main features of web 3.0 comparison Web 2.0
There is no such thing as web 3.0 (and web 2.0 was just a silly buzz word). All kinds of things are happening on the web now, not necessarily related, such as web apps, flat design, responsive design etc. You can’t capture all that in a buzz word. Leave that sort of thing to lamebrain marketers. 
For software versioning, changes such as 1.0 to 2.0 to 3.0 etc. signify that the new version of the software has major changes from the previous version.
“Web 2.0” or “Web 3.0” is more concept than anything specific as there was never a “Web 1.0”
Web 3.0 was a silly idea for making database designs much more flexible by totally ignoring normalisation and other rules for proper database design. It never amounted to anything much.
Web 2.0 on the other hand (accessing the server via ajax so as to not reload the entire page) is now a significant part of many web designs.
Lots of other things used those terms for marketing purposes without really being anything to do with the specific processes labelled as web 2.0 and web 3.0
There is nothing special that we call as web 3.0, this is mere acknowledging the latest technologies and their versions, as we all cannot find anything for Web 1.0
Web 2.0 uses the read write web, blogs, web applications, rich media, viral media, tagging or Folksonomy while sharing content and focusing on communities.
The Web 3.0 standard uses semantic web, drag n drop mash ups, widgets, user behavior or Me-onomy, advertisement, user engagement, consolidates dynamic content and focuses on individuals
I do not think that there is any kind of serious tools available for this version it may be a new version but mostly rumours are spread.