This document discusses various types of interactions between fungi and other organisms in ecosystems. It describes positive interactions like mutualism, commensalism, and protocooperation, where both or one organism benefits. Examples of mutualism provided include lichens, nitrogen-fixing bacteria and plants, and mycorrhizal associations between fungi and plant roots. Negative interactions discussed are exploitation like social parasitism, parasitism, and predation where one organism is harmed. Amensalism and competition are also summarized, where in amensalism one is harmed while the other is unaffected, and competition involves organisms competing for limited resources.