The document discusses key concepts of constitutions including that a constitution (1) establishes the fundamental rules and principles that govern a system of government, (2) serves as the supreme law of the land, and (3) establishes the basic framework and underlying principles of government including defining the powers of governmental branches. A constitution can be written or unwritten, and rigid constitutions are more difficult to amend than flexible ones. The document also provides details on interpreting constitutions and outlines ideal characteristics of written constitutions.