by Wendy Hall
In 2014 we celebrate the twenty-fifth anniversary of the birth of the idea that became the World Wide Web. In March 1989, while working at CERN, Tim Berners-Lee wrote a document entitled “Information Management – a Proposal” which described his ideas for creating a hypertext system that worked over the internet to enable physicists and other researchers around the world to easily exchange documents . I first heard about his ideas at the European Hypertext Conference (ECHT’90) in November 1990, where we presented our first paper on the Microcosm “open hypermedia system” that we had been developing at Southampton since 1989 . I first saw Tim and his colleague Robert Cailliau demonstrate the system they had by then called the World Wide Web at the ACM Hypertext conference (HT’91) in December 1991. This was the conference that famously rejected their paper about the WWW but it also marked the beginning of the revolution that the Web has brought to all our lives – the killer application for the Internet, the disruptive technology that has changed the way we communicate and manage information forever.
The Web in its purest form is a set of open standards and protocols for downloading documents from the Internet via hypertext links which are embedded in the documents. In the early 1990’s, explaining the concept of a global hypertext system to people was incredibly difficult. Ted Nelson had been trying for decades. As more and more content was put on the Web, it became possible to at least show people a vision of a future in which linked documents became the norm for information exchange on the Internet. To me the Web lacked the richness that we had been exploring in the Microcosm system where the links existed as entities in their own right and could describe relationships between information objects. However, this was also part of Tim’s original vision of a web that not only linked documents but also linked data as he articulated at the first WWW conference in Geneva in May 1994.
“The web is a set of nodes and links. To a user, this has become an exciting world, but there is very little machine-readable information there … To a computer, then, the web is a flat, boring world devoid of meaning. This is a pity, as in fact documents on the web describe real objects and imaginary concepts, and give particular relationships between them. Adding semantics to the web involves two things: allowing documents which have information in machine-readable forms, and allowing links to be created with relationship values. Only when we have this extra level of semantics will we be able to use computer power to help us exploit the information to a greater extent than our own reading.” 
This was too complicated for a world that was just discovering linked documents to grasp. Over the next few years the Web exploded. Search engines like Google emerged to help us find information on it and as the browsers became more interactive the social networks that seem to define the Web today began to evolve. Tim was still talking about a web of linked data, or the Semantic Web as he called it, and wrote about it in his book Weaving the Web  but it didn’t seem to be emerging. The people taking it most seriously were the artificial intelligence community who were keen to theorise about it and started their own conference series on the Semantic Web in 2002.
But the linked data revolution was creeping up on us quietly rather than with the big bang by which the first Web seemed to appear. The Semantic Web community tracked its initially slow emergence through the linked data cloud, and the technical requirements were simplified . But in essence, it has emerged as a necessary part of the data revolution that has been a natural consequence of the development of the Web and the Internet. Driven initially by the scientific community and further fuelled by the movement towards open data in the public sector, businesses are rapidly realizing the advantages of harnessing the power of big data and the absolute need for linked data technology as part of these developments.
“… linked data is the next step for the Web. There are multiple benefits over and above traditional Business Intelligence. It’s cheaper and faster to implement. If knowledge is power, with linked data’s capability to compare internal with external data, there is the potential to pull information to provide unrivalled context on business strategy.” Anwen Robinson, Managing Director, Unit 4, Business Software 
The behemoths of the Internet, such as Google and Microsoft, having denied it for so long, are finally making linked data an integral part of their offerings. This quiet revolution is actually going to have a bigger and more far reaching impact that the initial Web revolution. Linked data will become an integral part of the development of data-driven systems architectures that will revolutionize the way we build and maintain information management systems over the next few years. They will supersede relational databases and unify the worlds of hypertext, document management and databases to create rich interlinked knowledge-based systems as envisaged by the pioneers such as Bush, Nelson and Englebart over fifty years ago.
The excellent set of articles about linked data in this special issue of the ERCIM news is timely indeed. Let the revolution begin.
 A. Fountain, et al.: “Microcosm: An Open Model for Hypermedia with Dynamic Linking”, proc. of ECHT'90, Paris, 1990, Cambridge University Press, 298-311
 T. Berners-Lee: “Weaving the Web”, Harper Collins, 1999
 N. Shadbolt, T. Berners-Lee, W. Hall: “The Semantic Web Revisited”, IEEE Intelligent Systems, 21(3), 96-101
 A. Robinson: “Think Link” http://www.bigdatarepublic.com 9/4/2013