Political party

A political party is an organized group of people or bodies who seek to capture political power through an election in order to run the affairs of a country. It often puts forward candidates for public office. In a democracy, leaders must "run for office" in an election. In a dictatorship, there is generally only one party allowed, that can approve a new leader without non-members having a choice.
About
A political party is similar to a faction, and can be the same thing. In some systems, members of one party in the legislature are all expected to vote the same way. The laws written by the party or faction with the majority of votes become adopted by the country, so this means whatever party is elected to over half the seats, gets to run the government. The next largest party is often called the "opposition". Sometimes when there are more than two parties with seats, no one party has over half of the seats. Then two or more parties might join to form what is called a "coalition".
Some parties are formed around a single issue or interest group. Others form policies to address all matters of government, known as a "platform".
Many political parties have a set of ideas and beliefs (called its "ideology"). People often describe these ideologies using words such as "conservative" and "liberal".
Common ideologies include environmentalism, socialism (ranging from social democracy to Marxism and Communism), conservatism, democracy, liberalism, and nationalism.
The law
Political parties can be against the law in some places. When some parties get a lot of power, they can make all other political parties illegal. For example, the Nazi Party did this in Germany, and the Communist Party did it in several countries. Some countries make extreme-right parties illegal (such as Vlaams Blok in Belgium). At other times, countries have outlawed far-left parties. For example, West Germany banned the Communist Party in 1956.
A handful of countries like China, North Korea and Cuba still have one-party dictatorships. In a few other dictatorships, such as Saudi Arabia, all political parties are banned and there is no parliament at all.
Importance in all big democracies
In all big democratic countries, parties are very important. But there are a few very small countries, such as the island of Jersey, where most politicians do not belong to any party and where parties do not matter much.
In some democracies, there are only two big political parties. For example, in the United States, there is the Democratic Party and the Republican Party. Some other parties exist but are very small and do not hold seats in Congress.
In other countries there are larger numbers of parties. In the German federal Parliament (or Bundestag), six parties have seats. In the United Kingdom, there are two big parties, one medium-sized party, and many small ones.
Parties in each country
List of political parties in Australia
List of political parties in Canada
List of political parties in France
List of political parties in Germany
List of political parties in Malaysia
List of political parties in New Zealand
List of political parties in Pakistan
List of political parties in the United Kingdom
List of political parties in the United States