According to Gilchrist, Constitution of a state is that body of rules or laws, written or unwritten which determine the organisation of government, the distribution of powers to the various organs of government and the general principles on which these powers are to be exercised. Whereas for Woolsey, Constitution is the collection of principles according to which the powers of the government, the rights of the governed and the relations between the two are adjusted.

The kinds of Constitutions:

i. Written Constitution: A written constitution means a constitution written in the form of a book or a series of documents combined in the form of a book. It is a consciously framed and enacted constitution. It is formulated and adopted by a constituent assembly or a council or a legislature.

ii. Unwritten Constitution: An unwritten constitution is one which is neither drafted nor enacted by a Constituent Assembly and nor even written in the form of a book. It is found in several historical charters, laws and conventions. It is a product of slow and gradual evolution. The government is organised and it functions in accordance with several well settled, but not wholly written rules and conventions.

iii. Flexible Constitution: A Flexible Constitution is one which can be easily amended. Several political scientists advocate the view that a flexible constitution is one in which the constitutional law can be amended in the same way as an ordinary law. Constitutional amendments are passed in the same manner by which an ordinary law is passed.

iv. Rigid Constitution: The Rigid Constitution is one which cannot be easily amended. Its method of amendment is difficult. For amending it, the legislature has to pass an amendment bill by a specific, usually big, majority of 2/3rd or 3/4th. For passing or amending an ordinary law, the legislature usually passes the law by a simple majority of its members.

v. Evolved Constitution: An evolved constitution is one which is not made at any time by any assembly of persons or an institution. It is the result of slow and gradual process of evolution. Its rules and principles draw binding force from the fact of their being recognised as ancient, historical, time-tested and respected customs and conventions.

vi. Enacted Constitution: An Enacted Constitution is a man-made constitution. It is made, enacted and adopted by an assembly or council called a Constituent Assembly or Constitutional Council. It is duly passed after a thorough discussion over its objectives, principles and provisions. It is written in the form of a book or as a series of documents and in a systematic and formal manner.