The national flag of the Republic of Korea, also known as the Taegeukgi, has three parts: a white rectangular background, a red and blue taegeuk in its center, accompanied by four black trigrams, one in each corner. Flags similar to the current Taegeukgi were used as the national flag of Korea by the Joseon dynasty, the Korean Empire, as well as the Korean government-in-exile during Japanese rule. South Korea adopted the Taegeukgi for its national flag when it gained independence from Japan on 15 August 1945.

Taegeuk is a Sino-Korean term meaning "supreme ultimate", although it can also be translated as "great polarity / duality". The term and its overall concept is derived from the Chinese Taiji, popularised in the west as the Yin and Yang. The symbol was chosen for the design of the Korean national flag in the 1880s. It substitutes the black and white color scheme often seen in most taijitu illustrations with blue and red, respectively, along with a horizontal separator, as opposed to vertical.