A constitution is a body of rules, regulations, and conventions that determine how a country or organization is governed. It is a set of principles and guidelines that establish the structure, powers, and limitations of government institutions, as well as the rights and freedoms of the citizens. A constitution can be written or unwritten and serves as the supreme law of the land, which means that all other laws and regulations must comply with its provisions. Constitutions can be amended or revised but usually require a specific process or procedure to do so.