Labor law, also known as individual or labor legislation, remains in principle a branch of civil law. It lies at the crossroads of two major legal disciplines: private law and public law.It belongs to private law insofar as it deals with relations between private individuals, and it is precisely the principles of civil law that provided its initial foundations. But it has moved further and further away from its original source. Indeed, public power has penetrated labor relations in a very accentuated way, restricting above all the freedom of employers, and sometimes even that of workers.In this book, we will highlight the definition of labor law, its evolution and its sources. But first, let's try to situate this subject in relation to other branches of law.