Israel has a parliamentary democracy system with partial separation of powers between the judicial branch on the one hand, and the legislative and executive branches on the other. The President is largely a ceremonial figurehead. The post was probably created in part by David Ben-Gurion to honor Chaim Weizmann (see Presidents of Israel). The President is elected by the Knesset.
120 members of the Knesset (parliament) are elected in nation-wide elections from party lists. The head of the party that has the best chance of forming a coalition (usually, but not necessarily the party with the largest number of mandates) is then chosen by the President to attempt to form a government. Since no party has ever won a majority, a coalition must be formed.
The Israeli system is not like the British system, in which members are elected from districts. Rather, it is like the French Fourth Republic system. The members are chosen from party lists, and are elected in proportion to the number of votes received by the party, according to the predetermined order of candidates that was presented to the elections commission. As a result, the members are not beholden to a particular constituency and some of the back-bench members of larger lists are virtual unknowns. In theory, this produces a system based on ideologies represented in the party platforms. In the early years of the state this resulted in the formation of numerous small lists. The law has been amended repeatedly to raise the minimum percentage required for a party to enter the Knesset. According to the latest revision (Bader-Ofer Law), a party that receives less than 2% of the vote gets no representation at all, and its votes are "lost" - they are distributed proportionately. Excess vote of different parties that passed the minimum may be traded according to prior agreement.
A peculiarity of the system is that even though members are elected to lists, the mandate belongs to the individual. Individuals or groups may split off from the main party taking their mandates with them. Often they do leave to form new lists and one person "factions," resulting in a bewildering array of tiny "parties" that usually exist for one Knesset session only. Individuals or groups that leave with the intention of forcing a change in their party often form "lists" rather than parties, indicating that the ideological platform is the same as that of the original party, but the personnel are different. Such lists (reshimot) usually last for one or two elections. The Rafi list of David Ben-Gurion was one such party.
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