EU climate law can be defined as all European Union legislation related to climate action. It is one of the most dynamic and fastest growing areas of EU law. This is perhaps best exemplified by the Union's recent efforts to establish a "European Climate Law" that intends to present a legal framework for achieving climate neutrality in the EU by 2050. Our book provides an introduction to EU climate mitigation law. We focus on the relationship between climate law and the energy sector: the use of energy is an important driver of climate change and the energy sector is responsible for the largest share of greenhouse gas emissions in the EU. These emissions are primarily the by-product of burning fossil fuels. Our book is the only one to outline and review the main features and implementation issues of EU climate mitigation law in relation to the energy sector.