|All Indians over the age of 18 have the right to vote in general elections [EPA]
National elections in India, held every five years, are conducted in staggered phases to allow for adequate security and logistical arrangements as the millions of eligible voters, who nearly equal the population of Europe, head to the polls.
As it is the world's largest exercise in democracy, the election is a daunting undertaking, further complicated by the vast tracts of land that comprise the country, and will take weeks to complete.
Here we seek to explain that process.
When is the vote this year and who all are involved?
The 2009 polls to elect a new Lok Sabha, or lower house of parliament, will be staggered over five dates: April 16, 23, and 30, as well as May 7 and 13.
Voting in some states will take place over several stages.
Do not expect any exit polls during the voting phase, as the Election Commission has banned them.
Vote counting is due on May 16, and the results are expected the same day.
Around 714 million people are eligible to vote, and almost four million officials will be administering the poll.
What is the system and structure of India's democracy?
It is a parliamentary republic in which citizens are charged with choosing who will run the federal and state governments. All Indians above the age of 18 have the right to cast a vote.
Since independence from Britain in 1947, there have been 14 general elections and more than 350 state elections.
India has a bicameral legislative structure, with parliament consisting of the Lok Sabha, or lower house, and the Rajya Sabha, or the Council of States.
A total of 543 of the Lok Sabha's 545 members are directly elected by popular vote to represent individual constituencies for five-year terms.
The number of parliamentary constituencies in a state depends upon the size and the population of the state. Two members are nominated by the president from the Anglo-Indian community.
| Sonia Gandhi led her Congress party to victory in the last general election [AFP]
The Rajya Sabha has 245 members serving staggered six-year terms. Most members are elected indirectly by the state and territorial legislatures in proportion to the state's population.
In the Indian parliamentary system, the executive is subordinate to the legislature, with the prime minister and his council being responsible to the Lok Sabha.
The executive, along with the Council of Ministers, is chosen from among the members of the winning party or coalition.
How is the vote organised?
The Election Commission had to negotiate a long list of potential obstacles when scheduling the poll: school exams, holidays, festivals, the harvest and even the monsoon were all taken into account.
And no, it did not take the IPL cricket tournament into account because it is a private affair. (The tournament has now been shifted to South Africa, as it clashed with the poll schedule and the government refused security cover).
The polling is conducted by government officials and held in schools and colleges, as well as at some other state-owned venues.
There are 828,804 polling centres, including one in Gujarat's Gir lion sanctuary, which serves a single voter.
Many new centres have been set up to reduce the time voters have to travel, often across hills and rivers.
Electronic voting machines, introduced countrywide in 2004, will be used this year as well.
The machines have the candidates' names and symbols next to the buttons that people press to cast their votes. The symbols are there to help illiterates.
Photo electoral rolls will be used for the first time on a national level for voter identification, in an attempt to prevent prevent fraud.
Who is competing?
There are two main coalitions competing for power: the United Progressive Alliance (UPA), which has been in government for the past five years, and the opposition National Democratic Alliance (NDA) which was in power prior to that, between 1999 and 2004.
The UPA is led by the Congress party, which dominated Indian politics for a long time before a decline, while the NDA is led by the Bharatiya Janata Party (BJP).
These two groupings are also up against an alliance of left-wing and regional parties who have united to form the so-called Third Front.
What are the issues?
Voters will be casting judgement on Congress's policies over the past five years, including a $2.2bn rural employment guarantee programme, arguably the world's largest such scheme, and a landmark right to information law.
The Congress is advertising rapid economic growth during its tenure and its investment in social policies and the country's power infrastructure. But growth has been hit over the past year, with job losses and rising costs likely to negate these achievements.
|The BJP is seeking to return to power after its 2004 defeat to Congress [EPA]
While economic growth is also high on the BJP agenda, it is highlighting India's internal security situation in the aftermath of the November 2008 Mumbai attacks. Its stand is that the government has been ineffectual in cracking down on terrorism.
It will also point out that Manmohan Singh, the incumbent prime minister and the Congress' choice this time around too, is just a figurehead for Sonia Gandhi, the Italian-born party chief.
What are the possible outcomes of the vote?
The increasing fragmentation of Indian politics and rising power of regional parties has caused problems for both of the main coalitions.
With neither having a clear advantage in the run-up to the elections, both have been scrambling to bolster their positions through regional alliances.
If the two main coalitions fail to win a clear majority, regional and leftist parties could play a crucial role. The Third Front could also try to form a government itself.
Large scale changes in the boundaries of constituencies since the last elections have made predictions even more difficult in a country where voters keep their real voting intentions a secret. In the past few elections, most opinion polls were way off target.
How did they fare in previous elections?
In 1984, Congress won 404 seats, but by 2004, that number had dropped to 145. In the same 1984 election, the BJP won just two seats, while in 2004 it won 138.
State and regional parties held 51 seats after 1991 elections, but were up to 154 seats by 2004.
Will the vote be free and fair?
India has a long track record of organising peaceful and orderly elections on a massive scale.
Voter intimidation and vote buying have decreased dramatically in the past decade.
What happens after the election results are out?
After the results are submitted, the president would invite the party or coalition that has won the most seats to form the government.
The new government might be required to prove its majority through a vote of confidence. This means securing a simple majority in the 545-member lower house.