The Indian election starting Thursday is an exercise in a democracy the likes of which the world has never seen.
One-eighth of the world's population -- roughly 900 million people -- are eligible to vote over April and May in the largest democracy on the planet.
It is a logistical undertaking unrivalled in scale.
Ballots will be cast at a million voting booths across the world's second-most populous nation, from the Himalayas in the snowy north to the tropical coasts more than 3,000 kilometres (1,860 miles) away to the south.
Here's what you need to know about the biggest election in history: