Proportional representation is a system used to elect a country's government. If proportional representation is used in an election, a political party that wins 10% of the vote, will win 10% of the seats in parliament and a party that wins 20% of the vote, will win 20% of the seats.
If a party wins over 50% of the vote, it wins over 50% of the seats and can form a government, however this does not happen very often because most countries have lots of different political parties. If no party wins over 50% of the vote, then a coalition government usually has to be formed, where a government is formed from two or more different political parties, who together have over 50% of the seats in parliament.
Countries which use proportional representation include: Austria, Argentina, Belgium, Brazil, Bulgaria, Czech Republic, Denmark, Estonia, Finland, Greece, Iceland, Ireland, Israel, Netherlands, Norway, Poland, Portugal, Romania, Russia, South Africa, South Korea, Spain, Sweden, Switzerland and Turkey.
Countries which have systems that are similar or use semi-proportional representation include: Australia, Germany, Hungary, India, Republic of Ireland, Italy, Japan, Mexico, New Zealand, Scotland, Thailand and Wales.