A Constitution can be classified into two types
1. On the basis of its physical form, a constitution can be classified into written and unwritten.
2. On the basis of the amendment procedure (procedure for making changes to the Constitution), a Constitution can be classified into rigid and flexible.
A written constitution is single, formal document that describes the arrangement of governance in a country. It is framed in a systematic manner, usually by a representative body called the constituent assembly after many deliberations and discussions and therefore is also known as codified Constitution or enacted Constitution. It also specifies the date of its enactment. A written constitution is generally rigid in nature, i.e., a defined procedure which is different from the procedure of making an ordinary legislation is laid down to amend it, examples are – American Constitution and Indian Constitution
An unwritten Constitution is not written in a single document. It is derived from a number of sources that are part written and part unwritten, including conventions, traditions, customs, Acts of Parliament and the common law, and hence is also called a cumulative Constitution. It evolves over a period of time and therefore is also known as an evolved Constitution. An unwritten constitution is usually flexible in nature as the amendment procedure is simple and usually there is no difference between the procedure of making an ordinary legislation and the procedure of amending the Constitution, example – British Constitution.
However, no Constitution in this world is completely written or unwritten. Outside the Constitution, several conventions are followed in India. For example, according to the Constitution, to be chosen for the post of Speaker of Lok Sabha, the fundamental condition is to be a member of the Lok Sabha. But, in practice, an additional condition in the form of a convention – choosing the Speaker of Lok Sabha from the majority party – is followed in India. Also, though the British Constitution is largely unwritten, it is based on several written laws such as the Magna Charta 1215, the Bill of Rights 1689 and so on. Therefore, every written constitution, includes certain unwritten components and every unwritten constitution, includes certain written components.