The World Wide Web has a client-server architecture based on a resource identification scheme (URI), a communication protocol (HTTP) and a document format (HTML), which together allow easy access and exchange of information. The decentralized nature of the Web and its effectiveness in making information accessible have led to fundamental social and cultural change. Every product, from breakfast cereal to cars, has a presence on the Web. Businesses and other institutions have come to regard the Web as an interface, even the primary interface, with their customers. By providing ubiquitous access to information, the Web has reduced barriers erected by geographic and political borders in a profound way.