The Oxford English Dictionary defines a constitution as "a body of fundamental principles or established precedents according to which a state or organisation is governed". The Collins dictionary says a constitution consists of "the fundamental principles on which a state is governed, especially when considered as embodying the rights of subjects".

A constitution sets out how all the elements of government are organised and how power is carved up among different political units. It contains rules about what power is wielded, who wields it and over whom it is wielded in the governing of a country.

And, as a kind of deal or contract between those in power and those who are subjected to this power, a constitution defines the rights and duties of citizens, and the devices that keep those in power in check.

In the case of South Africa, these fundamental principles are contained in a single document: the Constitution of the Republic of South Africa 1996. It has been called the "birth certificate" of a new South Africa.

Our Constitution is the most important - or supreme - law of the land. No other law may conflict with it; nor may the government do anything that violates it. This brings us to the crucial topic of constitutional supremacy.