Over 650 counting observers have been deployed in 5 states to monitor the process. (Representational)
Following are the top 10 points:
The BJP is hoping to retain power in four states -- Goa, Manipur, Uttarakhand and Uttar Pradesh. The Congress is hoping for a comeback in Punjab.
The stakes are the highest in Uttar Pradesh, which with 80 parliamentary seats, holds the key to power at the Centre. A majority for the BJP in the 403-member Assembly would make it the first party to get a consecutive second term in more than three decades.
The Akhilesh Yadav-led Samajwadi Party, considered the biggest challenger of the BJP in Uttar Pradesh, has stitched up a rainbow coalition with smaller parties which it hopes will supplement its Muslim-Yadav support base with voters from the Other Backward Classes, who will be crucial in the eastern and western part of the state.
In Punjab, exit polls have predicted a big victory for Arvind Kejriwal's Aam Aadmi Party -- which has established its presence in the state -- pushing the ruling Congress to the number 2 position in the 117-member assembly.
The Congress has been a divided house for more than a year in the run-up to the polls. Its internal rivalries, including the battle between former Chief Minister Amarinder Singh and cricketer-turned politician Navjot Sidhu, had dominated headlines.
Mr Singh's new party, the Punjab Lok Congress, has joined hands with the BJP. The Akali Dal, which split for its longtime partner BJP after the countrywide protests over the farm laws, form the other contender in the multi-cornered contest.
A tough contest is expected in Goa, where the BJP managed to form government five years ago despite getting fewer seats than the Congress. Both parties are in a race to line up possible allies. The BJP is projecting confidence that it will have the support of estranged ally Maharashtrawadi Gomatak Party, which is currently partnering the Trinamool Congress.
Manipur was the second state where the Congress found itself out of power in 2017 despite being the single largest party, winning 28 of the 60 seats. The BJP, despite winning 21 seats, formed government with the help of the National People's Party and Naga People's Front. Meghalaya Chief Minister Conrad Sangma's National People's Party is also in fray this time, contesting 38 seats.
The Congress response this time has been early preparations - rushing its top leaders to both Goa and Manipur and closely guarding its flock of candidates. Senior leaders have also been dispatched to Uttarakhand, where a tight race is expected.
Many exit polls have predicted a hung assembly in Uttarakhand, a scenario where the role of Independents and marginal players like AAP, SP, BSP and the UKD will become significant in government formation. The BJP and Congress are locked in straight contests on 40 to 45 of the 60 seats, while the regional outfits make the fight triangular on 25-30 seats.
