General elections are due to be held in India in April or May 2019 to constitute the 17th Lok Sabha. Assembly elections of Andhra Pradesh, Arunachal Pradesh, Odisha, and Sikkim will be tentatively held simultaneously with the general election.
The current ruling party is the Bharatiya Janata Party, which runs the national government. The main opposition is the Congress Party.
The 543 elected members of the Lok Sabha will be elected from single-member constituencies by first-past-the-post voting. The President of India nominates an additional two members.
Sources and further reading:
How India Runs the Biggest Elections in the World
Urjit Patel: the yes-man who finally said no to Indian PM Modi