This document discusses the intersection of the social web and semantic web. It defines key concepts like collective intelligence, folksonomy, and collective knowledge systems. Examples are given of how structured data like locations can provide context for unstructured user-generated content like travel stories. Challenges are noted around sharing tagging data and a lack of standardized ontologies. The document argues semantic web technologies could help collective knowledge systems by enabling sharing of tagging data and structured information like a world destination hierarchy.