The work "Criminal Law - Concepts and Institutions of the General Part" deals with the General Part of the new Penal Code (Law 4619/2019) which came into force on 1.7.2019 and is updated up to Law 4637/2019. It provides a concise and well-documented presentation of the General Part of Substantive Criminal Law, whose theoretical analysis is combined with many practical examples that help in better understanding the text. The method of processing the book's content is based on the numbering of all its paragraphs, with margin numbers and the correlation of these numbers with each other. This makes the study of the book easier, as the discussed topics are connected with each other, allowing the reader to have immediate and quick access to previous or subsequent concepts. The edition is complemented by an alphabetical index. It is a useful theoretical and practical aid for lawyers, judges, and students of criminal law.