Israel uses a proportional voting system that has led to repeated failures to form stable government coalitions.
Instead of electing individual members of the 120-seat parliament, or Knesset, voters choose party lists, with seats distributed according to the percentage of the vote received.
Parties are only eligible for seats if they pass a threshold, which was raised last year from two percent to 3.25 percent.
That move was slammed by the opposition as an attempt to force Arab parties out of parliament, but it instead saw them join forces in a united list.
There are 25 lists battling it out for seats but opinion polls predict that only 11 are expected to enter parliament.
After official results are announced, President Reuven Rivlin will have seven days to entrust forming the next government to a party leader who says he or she is ready to do so.
The leader then has 28 days to build a coalition, but Rivlin can extend the deadline by another 14 days if necessary.
If a coalition still fails to emerge, he can assign another party leader to the task, again with a 28-day deadline.
If this bid fails as well, Rivlin can then assign the task to a third person. But if the person chosen is unable to form a government within 14 days then the president calls a new election.
In general, the leader whose party wins the most votes is tasked with forming a coalition, but this is not mandatory.
No party in Israel has ever been able to secure the necessary 61-seat majority to rule alone.
Twice -- in 1996 and 1999 -- Israelis voted directly for a prime minister as well as for a party list. In 2001, a special prime ministerial election was also held after then-Labour premier Ehud Barak was unable to win the Knesset's support.
Just six of the past 19 parliaments have been able to complete their four-year mandate.