The Imjin War (Korean: 임진왜란; Hanja: 壬辰倭亂) was a series of two Japanese invasions of Korea: an initial invasion in 1592 also individually called the "Imjin War", a brief truce in 1596, and a second invasion in 1597 called the Chŏngyu War (정유재란; 丁酉再亂). The conflict ended in 1598 with the withdrawal of Japanese forces from the Korean Peninsula after a military stalemate in Korea's southern provinces.

The invasions were launched by Toyotomi Hideyoshi with the intent of conquering the Korean Peninsula and China proper, which were ruled by the Joseon and Ming dynasties, respectively. Japan quickly succeeded in occupying large portions of the Korean Peninsula, but the contribution of reinforcements by the Ming, as well as the disruption of Japanese supply fleets along the western and southern coasts by the Joseon Navy, forced the Japanese forces to withdraw from Pyongyang and the northern provinces. Afterwards, with righteous armies (Joseon civilian militias) conducting guerrilla warfare against the occupying Japanese forces and supply difficulties hampering both sides, neither force was able to mount a successful offensive or gain any additional territory, resulting in a military stalemate. The first phase of the invasion ended in 1596, and was followed afterwards by ultimately unsuccessful peace negotiations between Japan and the Ming.

In 1597, Japan renewed its offensive by invading Korea a second time. The pattern of the second invasion largely mirrored that of the first. The Japanese had initial successes on land, capturing several cities and fortresses, only to be halted and forced to withdraw to the southern coastal regions of the peninsula. However, the pursuing Ming and Joseon forces were unable to dislodge the Japanese from these positions, where both sides again became locked in a ten-month-long military stalemate.

With Toyotomi Hideyoshi's death in 1598, limited progress on land, and continued disruption of supply lines by the Joseon Navy, the Japanese forces in Korea were ordered to withdraw back to Japan by the new governing Council of Five Elders. Final peace negotiations between the parties followed, and continued for several years, ultimately resulting in the normalization of relations.

In Korean, the first invasion (1592–1593) is called the "Japanese Disturbance of Imjin" (倭亂), where 1592 is an imjin year in the sexagenary cycle. The second invasion (1597–1598) is called the "Second War of Jeong-yu" (丁酉). Collectively, the invasions are referred to as the "Imjin War".

In Chinese, the wars are referred to as the "Wanli Korean Campaign", after the reigning Chinese emperor.

In Japanese, the war is called Bunroku no eki (文禄の役). Bunroku referring to the Japanese era name spanning the period from 1592 to 1596. The second invasion (1597–1598) is called Keichō no eki (慶長の役). During the Edo period (17–19th centuries), the war was also called Kara iri (唐入り), "entry into Tang", the dynasty whose name is synonymous with China.

In 1392, General Yi Sŏnggye led a successful coup to take political power in Korea from U of Goryeo. Seonggye's followers forced him to take the crown as Taejo of Joseon, thus establishing a new dynasty. In search of justification for its rule, the new regime received recognition from China and integration into the Chinese tributary system within the context of the Mandate of Heaven. Within this tributary system, China assumed the role of a "big brother", with Korea maintaining the highest position among the tributary states, which also included countries such as the Ryukyu Kingdom, Lan Xang, Đại Việt, and the Ayutthaya Kingdom, in return for accepting the subservient tributary role of a "younger brother".