The Communist Party Of India (CPI) was formed on December 26, 1925. The Communist Party of India (Marxist) split from the Communist Party of India and became a new political party in 1964.
The CPI(M) was formed at the Seventh Congress of the Communist Party of India held in Calcutta during November 1964. The formation of a new party was due to the revisionism in the communist movement and the principles of Communism inside India and the whole world. CPI(M) aims at applying Marxism-Leninism to Indian conditions and forming strategies for a democratic revolution which can better the Indian life.
The CPI(M) had a tremendous and steady growth since its formation in 1964. The number of official members grew from 118,683 (at the time of its formation), to more than 850,000.
The party declares its agenda officially like this-"The Communist Party of India (Marxist) is the revolutionary vanguard of the working class of India. Its aim is socialism and communism through the establishment of the state of dictatorship of the proletariat. In all its activities the Party is guided by the philosophy and principles of Marxism-Leninism which shows to the toiling masses the correct way to the ending of exploitation of man by man, their complete emancipation. The Party keeps high the banner of proletarian internationalism."
Source: http://cpim.org