The international human rights system is founded on the idea that all human beings have the same set of fundamental rights. The challenge is to give substance to the abstract notion of equality by translating it into concrete legal formulations that make clear which forms of unequal treatment are legitimate. This chapter explains how this challenge has been addressed in international human rights law. It discusses what, in general terms, equality and non-discrimination can be interpreted to mean. The chapter gives an overview of the different norms guaranteeing equality and non-discrimination in international human rights law. It explains the concepts of direct and indirect discrimination, and considers the requirements for a difference in treatment to be justified under international human rights law. Finally, the chapter sets out the different sorts of obligations that the right to equality imposes on states, in particular their duty to take positive action to ensure everyone can enjoy this right.