Coalition government
The 2010 United Kingdom general election ultimately resulted in a coalition government led by David Cameron (left) and Nick Clegg; this picture was taken shortly after they took office as Prime Minister and Deputy in May 2010. Coalitions are rare in British politics but common elsewhere.
In a multi-party democracy, a coalition government is one in which two or more political parties agree to share power. Coalitions may be formed in times of national crisis or political turmoil, though they are the norm in most European countries and are common in Japan even when one party has a working majority.
Coalition governments are most characteristic of parliamentary governments (e.g., Westminster system). Typically, the head of state will be outside the government and will approve the ruling coalition, to be led by the head of government.
A coalition need not include the party that received the most votes, as long as the coalition puts together a sufficient number of votes to be recognized. This is the current situation in the State of Israel.
Where two parties dominate the political system, such as in the United States of America or, until 2010, the United Kingdom, coalitions are rarely formed because elections typically result in a government with a majority of seats in the chamber and an opposition party with enough representation to form an effective counterweight to it. An exception is Japan, where factionalism and consensus politics often results in a drive to form coalitions even when the winning party has a firm majority; for example, the governing Democratic Party of Japan formed a coalition with the People's New Party and the Social Democratic Party in 2009, though the alliance with the SDP lasted less than a year.