New Delhi, India (BBN)-Indians have begun voting in the world's biggest election, with the ruling Congress party pitted against the Hindu nationalist BJP opposition, reports BBC.
The nine-phase ballot begins on Monday and concludes on 12 May. Votes will be counted on 16 May.
More than 800 million Indians are eligible to vote in a poll dominated by corruption and high inflation.
A new anti-corruption party, the AAP, is also contesting the elections after a spectacular result in local polls.
The AAP (Aam Aadmi, or Common Man's Party) made a strong showing at the state assembly polls in the capital, Delhi, and is standing for all the seats in the parliament.
Several smaller regional parties are also in the fray and if no single party wins a clear majority, they could play a crucial role in government formation.
The Lok Sabha (lower house of parliament) has 543 elected seats and any party or a coalition needs a minimum of 272 MPs to form a government.
Prime Minister Manmohan Singh has already said he is stepping down and the Congress is being led by Rahul Gandhi, the latest member of India's influential Nehru-Gandhi dynasty.
The BJP is being led by the charismatic and controversial Hindu nationalist leader Narendra Modi.
Modi, who is ahead in all the pre-election surveys, is the leader of Gujarat state, which witnessed one of India's worst anti-Muslim riots in 2002.
Some 814 million voters - 100 million more than at the last elections in 2009 - are eligible to vote at 930,000 polling stations, up from 830,000 polling stations in 2009.
Electronic voting machines will be used and will, for the first time, contain a None of the Above (Nota) button - an option for voters who do not want to cast their ballot for any of the candidates.
On the first day of voting, polling is taking place in six constituencies in two states in the north-east - five in Assam and one in Tripura.
The BBC's Sanjoy Majumder in Assam says the first voters have cast their ballots in the state, with many others queuing up outside polling stations.
"We need good people in government," said a woman voter, who had queued up outside a high school for girls where polling was taking place.
The area is dotted with plantations growing the world-famous Assam tea and has more than six million eligible voters.
Many of them say they are disenchanted with rising prices and a feeling that this part of India has been neglected by politicians because of its distance from Delhi, our correspondent says.
Assam is a Congress party stronghold but the opposition BJP is hoping to make inroads.
The Congress party has promised "inclusive growth" if it returns to power.
In its election manifesto, the party has promised a raft of welfare schemes, including a right to healthcare for all and pensions for the aged and disabled.
The BJP has yet to come out with its manifesto but in his election speeches across the country, Mr Modi has promised economic development, jobs for the youth and a corruption-free government.
POLLING DAYS
7 April - 2 states, 6 constituencies
9 April - 5 states, 7 constituencies
10 April - 14 states, 92 constituencies
12 April - 3 states, 5 constituencies
17 April - 13 states, 142 constituencies
24 April - 12 states, 117 constituencies
30 April - 9 states, 89 constituencies
7 May - 7 states, 64 constituencies
12 May - 3 states, 41 constituencies
Counting of votes - 16 May
BBN/ANS/AD/07Apr14-3:20 pm (BST)