What is law? It is a simple question, but the answer is complex. When we ask this question we expect a conceptual definition of law in the answer. There are different definitions according to different theories of law. The philosophy of law argues a justification of the meaning of law and value of law in the intersection between ethics and law. This book is an introduction to the philosophy of law, with a critical analysis of its theories and the main concepts (human dignity, freedom, justice, injustice, tolerance). Each concept is analyzed both on a theoretical and a practical level. The book, in each paragraph, is divided into two sections: a theoretical one and a practical one, with final questions on the main points and many concrete examples that allow the application of the concepts learned on a theoretical level (case studies, critical analysis of documents, norms, and judgments).