According to wikipedia the Semantic Web is an evolving extension of the World Wide Web in which web content can be expressed not only in natural language, but also in a format that can be read and used by automated tools, thus permitting people and machines to find, share and integrate information more easily. It derives from W3C director Tim Berners-Lee‘s vision of the Web as a universal medium for data, information, and knowledge exchange.
This sounds at least to me very abstract. Bernhard Angerer, Co-founder of Semantic Business Solutions explained me his vision how companies might benefit from the semantic web.
Tim Berner’s-Lee vision of the semantic web:I have a dream for the Web [in which computers] become capable of analyzing all the data on the Web – the content, links, and transactions between people and computers. A ‘Semantic Web’, which should make this possible, has yet to emerge, but when it does, the day-to-day mechanisms of trade, bureaucracy and our daily lives will be handled by machines talking to machines. The ‘intelligent agents’ people have touted for ages will finally materialize.