Industrial symbiosis, a research topic which focuses on how firms can collaborate over energy, utilities, materials or services, has seen considerable interest and growth in recent years due to the popularity of the circular economy. The topic has been identified as an approach for the circular economy in both the scientific literature and policy documents, applying many of the concepts of the circular economy to improve resource efficiency. The chapter provides a review of the topic, the state-of-the art in the research field, connections to the circular economy and on the needs for further research.