Isaac Herzog, co-leader of Zionist Union party, smiles at his party's headquarters in Tel Aviv March 16, 2015. [Photo/Agencies]

Here are some key facts relating to the elections:

- A total of 24 parties are vying for the 120 seats in the single-chamber parliament, the Knesset, Israel's 20th. Largely because of mergers of several parties, there are fewer parties than the last election, but only about 12 parties are expected to get enough votes to be represented in the Knesset.

- Knesset elections are based on the vote for a party rather than for individuals. Knesset seats are assigned in proportion to each party's percentage of the total national vote. The threshold for a party to be represented in the parliament was raised in 2014 to at least 3.25 percent of the total votes cast.

- There are 5,881,696 eligible voters and 10,119 polling stations across the country. Election day is a holiday in order to enable all potential voters to participate. Voter turnout in 2013 election was 67.8 percent.