This series of web pages introduces climate science in a sequence that illustrates different aspects of the climate system. Natural and human influences on climate are presented here, as well as the effects of interactions between parts of Earth's systems. Special emphasis is placed on the methods that scientists use to study the climate and make predictions about future impacts, as this is a topic that is sometimes misunderstood. The overarching Guiding Principle states that humans can take actions to reduce climate change and its impacts, which is a key part of teaching climate science. Taken together, these concepts describe climate literacy.