Over time the corpus of rights and obligations under the European Convention on Human Rights has developed into and is perhaps best understood as a system of autonomous concepts, with the European Court of Human Rights acting as its master of conceptualisation. The Companion to the European Convention on Human Rights seeks to identify and explain what these concepts are, how they have evolved, and how they have been applied by the Court. The Companion presents the first compilation and analysis of nearly 300 ECHR notions on Convention rights, principles, procedures and institutions.