Special Issue on Semantic Web

Fifteen years ago Tim BernersLee, James Hendler, and Ora Lassila formulated the idea of a Semantic Web that extends the standard Web by giving information well-defined and computer-processable meaning with the goal of enabling computers and people to work in cooperation. Since then, this idea led to many developments. For example, the crowed-sourced community effort DBpedia makes a large part of the free encyclopedia Wikipedia available in a structured and machine processable format. The English version of DBpedia alone describes 4.58 million things (1,445,000 persons, 735,000 places, 411,000