A constitution is the fundamental set of principles or established precedents that constitute the legal basis of a polity, organization, or entity, defining how it is governed. It outlines the framework for government, the distribution of powers, and the rights of individuals. Constitutions can be written (codified) or unwritten (uncodified) and often include provisions that limit state power and protect fundamental rights. Key points about constitutions:

• They serve as the supreme law from which all other laws derive.
• Constitutions may be written as a single document or spread across multiple documents, court cases, and treaties.
• They regulate the relationship between the executive, legislature, judiciary, and citizens.
• Constitutions can be amended, often requiring a special process and supermajority.
• Examples: The U.S. Constitution is the oldest written constitution still in force. The Constitution of India is the longest written one. The UK has an uncodified constitution.

Different levels of organizations, from countries to companies, can have constitutions. Some limit governmental powers and explicitly protect citizens' rights, while some autocratic states may have constitutions that are less adhered to in practice. Constitutions may also have a preamble declaring the state's goals and values and set rules for governmental operation and citizen rights. The constitution is often considered the highest legal authority within a state or organization.