A constitution may be written or unwritten, rigid or flexible. A written constitution, incorporates within its field, the principles regarding the structure of the government in the form of written documents.
A Rigid constitution is that which cannot be changed easily and a flexible constitution is that which can be amended without much difficulty. No constitution of Great Britain is flexible in nature, while that of the U.S.A quite rigid.
Written Constitutions, with exception is generally rigid and Unwritten Constitution is mostly flexible. Hence, we shall examine merits and demerits of Rigid and Written Constitution on the one hand and those of Flexible and Unwritten Constitution on the other hand.