Introduction:
The constituent assembly of India was formed to draft the Constitution of India, which came into effect on January 26th, 1950. The constituent assembly consisted of representatives from various political parties, communities, and regions.

Explanation:
The constituent assembly was formed in 1946, after the Cabinet Mission Plan was announced. The plan proposed the formation of a constituent assembly to draft the Constitution of India. The assembly consisted of 389 members, including 292 from British India and 93 from the princely states.

The first meeting of the constituent assembly was held on December 9th, 1946, at the Constitution Hall in New Delhi. Dr. Sachchidananda Sinha was elected as the temporary chairman of the assembly. Later, Dr. Rajendra Prasad was elected as the President of the constituent assembly.

The constituent assembly took almost three years to draft the Constitution of India. The drafting committee was formed on August 29th, 1947, with Dr. B.R. Ambedkar as its chairman. The committee presented the final draft of the Constitution on November 4th, 1949.

Conclusion:
Thus, the constituent assembly of India started functioning in 1946. The assembly played a crucial role in the making of the Constitution of India, which is the longest written constitution in the world.