What is a capital for a country?

Some examples for capitals of countries include:

• Washington, D.C., United States
• Ontario, Canada
• Mexico City, Mexico
• Brasília, Brazil
• Buenos Aires, Argentina
• Madrid, Spain
• London, United Kingdom
• Berlin, Germany
• Moscow, Russia
• Jerusalem, Israel
• Beijing, China
• Tokyo, Japan
• Sydney, Australia
• Wellington, New Zealand
• Pretoria, South Africa
• Cairo, Egypt