Flag of South Korea in the context of "Republic of Korea"

Taoism or "Do" is thought to be the earliest state philosophy for the Korean people. However, its influence waned with the introduction of Buddhism during the Goryeo kingdom as the national religion and the dominance of neo-Confucianism during the Joseon dynasty. Despite its diminished influence during those periods, it permeated all strata of the Korean populace, integrating with its native animism as well as Buddhist and Confucian institutions, temples, and ceremonies. The Taoist practice in Korea developed, somewhat in contrast to China, as an esoteric meditative practice in the mountains taught by the "mountain masters" or "mountain sages".

One of Korea's well-known founding myths in which a tiger and a bear seek to become human during an encounter with Hwanung may be viewed as a Taoist parable. The exact origin, despite various theories by historians, is in question because the royal records maintained by the early Korean kingdoms were destroyed during the two occasions in which the royal libraries were burned by invading Chinese armies. Later attempts to study the history and philosophy of Korean Taoism were suppressed during the Joseon kingdom which embraced only Confucianism as the proper field of study.

Taegeuk (Korean: 태극; Hanja: 太極, Korean pronunciation: [tʰɛgɯk̚]) is a Sino-Korean term meaning "supreme ultimate", although it can also be translated as "great polarity / duality / extremes". 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.

South Koreans commonly refer to their national flag as taegeuk-gi (태극기), where gi (기) means "flag" or "banner". This particular color-themed taegeuk symbol is typically associated with Korean traditions and represents balance in the universe; the red half represents positive cosmic forces, and the blue half represents the complementary or opposing, negative cosmic forces. It is also used in Korean shamanism, Confucianism, Taoism, and Buddhism.