Conceptions

Conceptions — very important component of Civilization IV. If you will know all conceptions well, you will be able to play more professional.
Full list:

• Animals
• Air Units
• Barbarians
• Borders
• Buildings
• Cities
• City Network
• Civics
• Combat
• Commerce
• Culture
• Diplomacy
• Draft
• Exploration
• Food
• Golden Ages
• Great People
• Happiness
• Health
• Hurry Production
• Improvements
• Leaders
• Maintenance
• Maps
• Movement
• Nukes
• Production
• Promotions
• Religion
• Research
• Resistance
• Resources
• Revolution
• Spaceship
• Specialists
• Spies
• Technology
• Terrain
• Trade
• Treasury
• United Nations
• Units
• Victory
• War
• War Weariness
• Wealth
• Wonders