Most nations today have a Parliamentary or Presidential democracies. Both of them have elections to choose the leaders just in different ways. Parliamentary democracies work by having voters elect lawmakers to represent them in parliament . The party that wins a legislative majority forms a new administration. If no party has majority then a few parties come together to form a ruling coalition. The legislative majority selects a member of parliament to serve as the nations prime minister who usually is the leader of the party with the most seats. The prime minister then choses members of parliament to head key government ministries, or executive branch departments.
There is no clear cut separation between the executive and legislative branches of government. The legislative majority usually vote with the prime minister on key issues. This makes it easier to get legislation passed then in a presidential system however because of the lack of separation means their is no real check on the prime minsters power. The prime minister may also lack the legitimacy and/or public support of an president. Only as long as the prime minister has the support of parliament can they stay in power other wise parliament can approve a vote of no confidence forcing the prime minister to resign at that point a election may be held to get a new legislative majority. This can make the government unstable.
Pros and cons.
In a parliamentary Democracy legislations can be passed easier and gridlocks are near impossible. But prime ministers have no real check on their power and don't have as much public support that a president usually has.
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