In 2013, twenty-five Member States of the European Union decided to take European patenting and patent enforcement to a next level. They agreed on a common patent title and a common patent court, i.e. the new Unitary Patent and the Unified Patent Court. Unfortunately, the implementation phase of the new patent package appeared to be a bumpy ride: non-participating Member States attacked the legal texts before the EU Court of Justice, the Rules of Procedure of the Unified Patent Court were subject to extensive debates, the Brexit caused the UK to step out of the system, an action before the constitutional court in Germany resulted in years of delay, etc. Nevertheless, the unitary patent package appeared to be a survivor. On 1 June 2023, the Unified Patent Court could finally open its doors with seventeen EU participating Member States. At the same time the first Unitary Patents could officially be registered. From then on, companies, research institutions, and individuals are able to obtain not only a patent title with immediate effect in the participating EU Member States, but also a court decision on infringement or validity of a European or Unitary Patent with immediate effect in all the participating Member States. The authors of this book, one being a leading Belgian IP lawyer who had a hand in the legal texts of the Unitary Patent and the other being a reputed Belgian intellectual property appeal judge who is currently (part-time) UPC judge at the local division in Brussels, were the first in 2013 to publish an introduction to the Unitary Patent and the Unified Patent Court. In 2017, they published the first edition of the current book. In this second edition of the book, they now present a comprehensive description of all aspects of this new patent and enforcement system. This book not only describes in detail all the provisions regarding the new patent and the new court, but also explains the history and the rationale behind certain choices. This book unravels all legal texts regarding the Unitary Patent and the Unified Patent Court, including the Rules of Procedure and all other Rules governing the Unitary Patent and the Unified Patent Court. This book also includes flowcharts summarizing the important phases of the proceedings before the Unified Patent Court. For its deeply informed insights into the practical functioning of this revolutionary new patent and litigation system, this extraordinary book is a must-have on the bookshelf of anyone involved or interested in European patenting.