The korean national flag, Taegeukgi (태극기) takes its name from the taegeuk circle in the center of the flag. It is divided equally and in perfect balance. The upper red section represents yang and the blue lower section represents yin,  an ancient symbol of the universe.

The powerful cosmic forces that oppose each other, achive perferct harmony and balance: darkness and lightness, heat and cold, day and night, positive and negative…

The trigram bars give you the same ideas of opposition and balance. The three unbroken lines stand for heaven; the opposite three broken lines represent earth. At the lower left the fire is represented and at the top right the water. The white background shows the purity of the Korean people and their peace-loving spirit.

The flag was suggested by Qing Dynasty diplomat Ma Jianzhong in 1882 and the Taegeukgi was officially declared the national flag of Korea by King Gojong on March 6, 1883. The Taegeukgi was both a symbol of the independence movement and of resistance during the Japanese occupation and mere possession of the flag was punishable by death.

A popular variant in Korea is the Sam-Taegeuk (三太極), which adds a yellow lobe, representing man, to the red and blue.