The Sri Lankan Civil War was a conflict fought on the island of Sri Lanka. Beginning on July 23, 1983, there was an intermittent insurgency against the government by the Liberation Tigers of Tamil Eelam (the LTTE, also known as the Tamil Tigers), a separatist militant organization which fought to create an independent Tamil state called Tamil Eelam in the north and the east of the island. After a 26-year military campaign, the Sri Lankan military defeated the Tamil Tigers in May 2009, bringing the civil war to an end.

For over 25 years, this civil war caused significant hardships for the population, environment and the economy of the country, with an estimated 80,000–100,000 people killed during its course. During the early part of the conflict the Sri Lankan armed forces adopted widespread rape and indiscriminate killings of civilians as reprisal attacks on Tamil population. These uncontrolled reprisal attacks gave rise to terrorism on the part of LTTE to control the Sri Lankan armed forces' rapes and indiscriminate killings. The tactics employed by the Liberation Tigers of Tamil Eelam resulted in their being branded as a terrorist organization in 32 countries, including the United States, India, Australia, Canada and the member nations of the European Union. The Sri Lankan government forces have also been accused of human rights abuses.

A civil war is a war between organized groups within the same nation state or republic, or, less commonly, between two countries created from a formerly united nation state. The aim of one side may be to take control of the country or a region, to achieve independence for a region, or to change government policies. The term is a calque of the Latin bellum civile which was used to refer to the various civil wars of the Roman Republic in the 1st century BC.

A civil war is a high-intensity conflict, often involving regular armed forces, that is sustained, organized and large-scale. Civil wars may result in large numbers of casualties and the consumption of significant resources.

Civil wars since the end of World War II have lasted on average just over four years, a dramatic rise from the one-and-a-half year average of the 1900-1944 period. While the rate of emergence of new civil wars has been relatively steady since the mid-19th century, the increasing length of those wars resulted in increasing numbers of wars ongoing at any one time. For example, there were no more than five civil wars underway simultaneously in the first half of the 20th century, while over 20 concurrent civil wars were occurring at the end of the Cold War, before a significant decrease as conflicts strongly associated with the superpower rivalry came to an end. Since 1945, civil wars have resulted in the deaths of over 25 million people, as well as the forced displacement of millions more. Civil wars have further resulted in economic collapse; Burma (Myanmar), Uganda and Angola are examples of nations that were considered to have promising futures before being engulfed in civil wars.

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka (ⁱ/ʃriː ˈlɑːŋkə/, /sriːˈlɑːŋkə/, or /sriːˈlæŋkə/;Sinhala: ශ්‍රී ලංකාව, Tamil: இலங்கை), is a country off the southern coast of the Indian subcontinent in South Asia. Known until 1972 as Ceylon ( /sɨˈlɒn/, /seɪˈlɒn/, or /siːˈlɒn/), Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar, the Palk Strait, and lies in the vicinity of India and the Maldives.

As a result of its location in the path of major sea routes, Sri Lanka is a strategic naval link between West Asia and South East Asia. It was an important stop on the ancient Silk Road. Sri Lanka has also been a center of the Buddhist religion and culture from ancient times, being the nation where the Buddhist teachings were first written down as well as the oldest continually Buddhist country. Sri Lanka boasts a diverse range of cultures, languages and religions. The Sinhalese people form the majority of the population; Tamils, who are concentrated in the north and east of the island, form the largest ethnic minority. Other communities include Moors, Burghers, Kaffirs, Malays and the aboriginal Vedda people.