For committed nature conservationists, the reasons in favor of environmental protection are firm beliefs that are almost self-evident and serve as natural sources of motivation for responsible environmental action. However, it is beyond question that not everyone shares these beliefs. Environmental ethics examines the reasons and the standards derived from them that can and should guide our individual and collective actions and lifestyles in relation to non-human nature. In this introduction, environmental ethicist Konrad Ott presents the fundamentals of the discipline and spans a wide thematic arc from the causes of the environmental crisis to the current discussion on strong sustainability and the role of environmental ethics in political philosophy.