The work "Criminal Law - Concepts and Institutions of the General Part" deals with the General Part of the new Criminal Code (Law 4619/2019) which came into effect on July 1, 2019, and is updated to Law 4637/2019. It constitutes a concise and well-documented presentation of the General Part of Substantive Criminal Law, the theoretical analysis of which is combined with many practical examples that aid in a better understanding of the text. The method of processing the content of the book is based on the numbering of all its paragraphs, with margin numbers as well as the correlation of these numbers to each other. In this way, the study of the book becomes easier since the discussed topics are connected, allowing the reader to have immediate and quick access to previous or subsequent concepts. The edition is supplemented with an alphabetical index. It is a user-friendly theoretical and practical aid for lawyers, judges, and students of criminal law.