Somalia, officially the Federal Republic of Somalia, is the easternmost country in continental Africa. Stretching across the Horn of Africa, it borders Ethiopia to the west, Djibouti to the northwest, Kenya to the southwest, the Gulf of Aden to the north, and the Indian Ocean to the east. Somalia has the longest coastline on Africa's mainland. Somalia has an estimated population of 18.1 million, of which 2.7 million live in the capital and largest city, Mogadishu. As one of Africa's most ethnically homogenous countries, around 85% of its residents are ethnic Somalis. The official languages of the country are Somali and Arabic, though Somali is the main language. Somalia has historic and religious ties to the Arab world. The overwhelming majority of the population are Sunni Muslims.

In antiquity, Somalia was an important commercial centre. During the Middle Ages, several powerful Somali empires dominated the regional trade, including the Ajuran Sultanate, Adal Sultanate, and the Sultanate of the Geledi. In the late 19th century, the Somali sultanates were colonised by the Italian and British empires, who merged all of these tribal territories into two colonies: Italian Somaliland and British Somaliland. In 1960, the two territories united to form the independent Somali Republic under a civilian government. Siad Barre of the Supreme Revolutionary Council (SRC) seized power in 1969 and established the Somali Democratic Republic, brutally attempting to squash the Somaliland War of Independence in the north of the country. The SRC collapsed in 1991 with the onset of the Somali Civil War. The Transitional National Government of Somalia (TNG) was established in 2000, followed by the formation of the Transitional Federal Government of Somalia (TFG) in 2004, which reestablished the Somali Armed Forces.

At the end of 2006, a US-backed Ethiopian invasion overthrew the Islamic Courts Union (ICU), leading to the installation of the TFG in Mogadishu under an Ethiopian military occupation. The subsequent insurgency which emerged saw the ICU fragment into various rebel factions, including the militant group al-Shabaab, which waged a protracted conflict against Ethiopian forces. Al-Shabaab soon began asserting territorial control for the first time, and by late 2008 the insurgency had driven the Ethiopian army out of much of Somalia. In 2009, a new TFG government was established. By mid-2012, al-Shabaab lost most of its territories during fighting against the TFG and African Union troops. That same year, al-Shabaab pledged allegiance to al-Qaeda. The insurgents still control much of central and southern Somalia, and wield influence in government-controlled areas, with the town of Jilib acting as the de facto capital for the insurgents. A new provisional constitution was passed in August 2012, reforming Somalia as a federation. The same month, the Federal Government of Somalia was formed and a period of reconstruction began in Mogadishu.

Somalia is among the least developed countries in the world, as evidenced by its ranking in metrics such as GDP per capita and its position near the bottom of the Human Development Index, above only South Sudan. It has maintained an informal economy mainly based on livestock, remittances from Somalis working abroad, and telecommunications. It is a member of the United Nations, the Arab League, African Union, Non-Aligned Movement, East African Community, and the Organisation of Islamic Cooperation.

Samaale, the oldest common ancestor of several Somali clans, is generally regarded as the source of the ethnonym Somali. One other theory is that the name is held to be derived from the words soo and maal, which together mean "go" and "milk". This interpretation differs depending on region with northern Somalis imply it refers to go and milk in regards to the camel's milk, southern Somalis use the transliteration "sa' maal" which refers to cow's milk. This is a reference to the ubiquitous pastoralism of the Somali people. Another plausible etymology proposes that the term Somali is derived from the Arabic word for "wealthy" (zāwamāl), again referring to Somali riches in livestock.

Alternatively, the ethnonym Somali is believed to have been derived from the Automoli (Asmach), a group of warriors from ancient Egypt described by Herodotus. Asmach is thought to have been their Egyptian name, with Automoli being a Greek derivative of the Hebrew word S’mali (meaning "on the left hand side").

A Tang Chinese document from the 9th century AD referred to the northern Somalia coast — which was then part of a broader region in Northeast Africa known as Barbaria, in reference to the area's Barbars (Cushitic) inhabitants — as Po-pa-li.

The first clear written reference of the sobriquet Somali dates back to the early 15th century AD during the reign of Ethiopian Emperor Yeshaq I who had one of his court officials compose a hymn celebrating a military victory over the Sultanate of Ifat. Simur was also an ancient Harari alias for the Somali people.