The right to education has been recognized as a human right in a number of international conventions, including the International Covenant on Economic, Social and Cultural Rights which recognizes a right to free, compulsory primary education for all, an obligation to develop secondary education accessible to all with the progressive introduction of free secondary education, as well as an obligation to develop equitable access to higher education, ideally by the progressive introduction of free higher education. In 2021, 171 states were parties to the Covenant.