In the 2004 parliamentary elections in India, three major alliances played a significant role. These alliances were the National Democratic Alliance (NDA), the United Progressive Alliance (UPA), and the Left Front. Let's discuss each of these alliances in detail:

National Democratic Alliance (NDA):
- The NDA is a coalition of political parties formed in 1998, with the Bharatiya Janata Party (BJP) as its leading party.
- In the 2004 parliamentary elections, the NDA sought to secure a second term in power, with Prime Minister Atal Bihari Vajpayee as its candidate.
- The alliance consisted of several regional parties such as the Janata Dal (United), Shiv Sena, Akali Dal, and others.
- The NDA campaigned on the platform of economic development, national security, and good governance.

United Progressive Alliance (UPA):
- The UPA is a coalition of political parties formed in 2004, with the Indian National Congress (INC) as its leading party.
- In the 2004 parliamentary elections, the UPA aimed to challenge the ruling NDA and form the government.
- The alliance included parties like the Dravida Munnetra Kazhagam (DMK), Nationalist Congress Party (NCP), and several left-leaning parties.
- The UPA campaigned on the issues of inclusive growth, social welfare schemes, and secularism.

Left Front:
- The Left Front is a coalition of left-wing political parties, mainly the Communist Party of India (Marxist) (CPI(M)), Communist Party of India (CPI), and Revolutionary Socialist Party (RSP).
- The Left Front has traditionally been a strong force in states like West Bengal, Kerala, and Tripura.
- In the 2004 parliamentary elections, the Left Front allied with the UPA and extended its support to the formation of a non-BJP government at the center.
- The Left Front's key focus areas were the rights of workers, farmers, and marginalized sections of society.

Conclusion:
All three alliances - the National Democratic Alliance (NDA), the United Progressive Alliance (UPA), and the Left Front - were present during the 2004 parliamentary elections in India. The NDA sought a second term in power, the UPA aimed to challenge the ruling NDA and form the government, and the Left Front allied with the UPA to support the formation of a non-BJP government. These alliances played a crucial role in shaping the political landscape of India during that election.