The RDF (Resource Description Framework) is the markup language for describing the information and the resources on the web. Putting the information into an RDF files, makes the computer programs ("the web spiders") to search, to discover, to pick up, to collect, to analyze and to process the information from web. Semantic Web uses an RDF to describe the web resources.

If an information about the music, cars, tickets were stored in the RDF files, an intelligent web applications could collect the information from many of the different sources, combine the information, and present it to the users in a meaningful way.
The Information like this:

A Semantic Web is not an fast growing technology.One of the reasons for this is the learning curve. RDF was been developed by the people with the academic background in logic and the artificial intelligence. For the traditional developers it is not easy to understand. One of the fast growing language for building the semantic web applications is the RSS.