Search engines play a major role in the success and growth of the WWW. In doing so they in turn help shape the web: they create new business models, modify content creation and consumption practices, support new forms of user interaction, etc. Semantic Web technologies have the potential to greatly improve search; if they succeed, this will in turn speed up the growth and impact of the semantic web initiatives. Yahoo! has already announced important steps towards integrating semantic technologies to improve and open up its search engine to content publishers, consumers and advertisers. In my talk I will briefly discuss some of these initiatives.

However, the history of Information Retrieval has taught us that fundamentally improving search through the use of semantics is a hard scientific problem. So far, semantic technologies have been successful at improving search only in closed-domain areas, with controlled vocabularies and small ontologies. However, it is unclear how we may transfer these technologies to more open domains (or to the WWW at large). Even harder is the challenge of improving search through the use of automatically extracted semantic information from text. At Yahoo! Research, experts in computational linguistics, semantic web and information retrieval work together to better understand this problem and go beyond the current state of the art. During my talk, I will review several of our research projects in these areas, drawing from examples in computational advertising, entity ranking, question answering and query suggestion.