This paper describes a Semantic Annotation Tool for extraction of knowledge structures from web pages through the use of simple user-defined knowledge extraction patterns. The semantic annotation tool contains: an ontology-based mark-up component which allows the user to browse and to mark-up relevant pieces of information; a learning component (Crystal from the University of Massachusetts at Amherst) which learns rules from examples and an information extraction component which extracts the objects and relation between these objects. Our final aim is to provide support for ontology population by using the information extraction component. Our system uses as domain of study “KMi Planet”, a Webbased news server that helps to communicate relevant information between members in our institute
