Researchers at every stage of their scientific careers encounter unknown terms and concepts and require background and contextual knowledge to progress. That is why we created ScienceDirect Topics. Our free topic pages provide readers with a comprehensive database of reliable background and contextual knowledge making it easy to get up to speed with new and unfamiliar concepts. They connect you to summarized knowledge and act as a discovery tool for further trusted reading, making this the ideal environment for intuitive learning and for sparking your creativity.