The main discussion of the doc is in regards to the potential of "the semantic web." Wikipedia defines this concept as follows:
"The Semantic Web is an evolving development of the World Wide Web in which the meaning (semantics) of information and services on the web is defined, making it possible for the web to "understand" and satisfy the requests of people and machines to use the web content. It derives from World Wide Web Consortium director Sir Tim Berners-Lee's vision of a universal medium for data, information, and knowledge exchange."
Still not getting it? According to an unsophisticated yet helpful YouTube video, Intro to the Semantic Web, the problem that the semantic web addresses is, how are we going to make the Internet better? The answer lies in semantics. Computers don't understand the meaning behind the webpages they're showing us. If we can get computers to recognize what's in a webpage, they can learn what we're interested in. If they know that, they can help us find what we want... actively. The semantic web is about things (not documents)... people, places, events, music, movies, organizations, etc. That's the idea.