Web 2.0 makes our life easier day by day and lets us to access any information whenever and wherever we are with simple internet clients.
On the other hand, user contributed data (social media & networks) grows enormously so, we have to spend our time by eliminate unnecessary data and pick up useful ones. There are two ways to handle this situation; intelligent applications or meaningful data. When we consider development and maintaining costs intelligent applications would be a failure. Giving meaning to data seems more applicable, at this point semantic web plays the role.
Semantic web is the extension of the current web which delivers extra information
in well formed machine readable structure.
Web 2.0 is the new way of delivering information with user friendly designs, web services,
social networks, blogs, videos … etc.
Web 3.0 is the evolution of the Web 2.0.
Actually, Web 3.0 is going to be integration of social media with semantic web; adding semantic structure to user contributed data.
So, if you have machine readable data, smart agents can be developed to handle daily tasks you have to do. For example, if you need to buy a book, let it to be done by your agent. It will seek and find the cheapest book and give an order for you. It is not only for machines, it might change the way we surf the web. For example, semantic web for e-government projects aim to provide all necessary information in one place (website).
However, it might have some issues like security and privacy. Also, semantic structures will result in the rise of agents and new types of spams.
Semantic Web research areas have been increasing and spreading and more companies investing for theses technologies. I hope I can take part in these research projects and develop something useful.