About 900 million people are eligible to vote, nearly the combined population of Europe and Brazil, and 10 percent more than in the 2014 election.
About 432 million eligible voters are women. There are 15 million voters between 18 and 19 years of age.
In the first phase of the election, 1,279 candidates are contesting 91 constituencies, but only seven per cent of candidates are women. Of the 8,251 candidates in the last election, only 668 were women.
The Election Commission of India (ECI), an autonomous constitutional body, oversees the election with more than 300 full-time officials at its headquarters in New Delhi.
The fight is for 543 of the 545 seats in the lower house of parliament, the Lok Sabha.
The remaining two seats are reserved for the Anglo-Indian community, which traces part of its ancestry to Europeans who intermarried with Indians in the colonial era. These members are nominated by India’s president.
Modi won by 570,128 votes in Vadodara in his western home state of Gujarat in 2014, the highest winning margin of all candidates.
By Road, Boat and Elephant
The commission has set up about 1 million polling stations, 10 percent more than in 2014. No voter should be more than 2 km (1.2 miles) away from a polling station.
More than 11 million government officials will travel by foot, road, special train, helicopter, boat, and sometimes elephant, to hold the election.
Polling stations are often in remote areas. More than 80,000 stations lacked mobile connectivity and nearly 20,000 were in forest or semi-forest areas, a commission survey said last year.
A polling station in the Gir forest of western Gujarat state will be set up for just one voter, a Hindu monk.
Voting will take place over 39 days, in part to allow officials and security forces time to redeploy. Vote counting for all 543 constituencies is done in a single day.
The 2014 election cost 38.7 billion rupees ($552 million), according to commission estimates.
Cash, Drugs, Liquor
Some political parties and their supporters offer cash, drugs and liquor in exchange for votes.
The commission has seized 5.1 billion rupees ($73.6 million) in cash, some 21,500 kg of drugs worth 7.2 billon rupees, and 8.8 million liters of liquor valued at 1.8 billion rupees.
It seized 12 billion rupees in cash, liquor and drugs in the last election.
The commission used 1.8 million electronic voting machines in the last election.
Opposition groups say the machines can be tampered with and they want the commission to tighten its security measures to cross check votes in this election.
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