Colombia (IPAEng: kəˈlʌmbɪə), officially the Republic of Colombia ( , ), is a country in northwestern South America. Colombia is bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the northwest by Panama; and to the west by the Pacific Ocean. Colombia also shares maritime borders with Jamaica, Haiti, the Dominican Republic, Honduras, Nicaragua and Costa Rica. Tratados Internacionales limítrofes de Colombia Colombia is the 26th largest nation in the world and the fourth largest in South America (after Brazil, Argentina, and Peru). It has the 29th largest population in the world and the second largest in South America, after Brazil. Colombia has the third largest Spanish-speaking population in the world after Mexico and Spain.

The territory of what is now Colombia was originally inhabited by indigenous tribes including the Muisca, Quimbaya, and Tairona. The Spanish arrived in 1499 and initiated a period of conquest and colonisation which ultimately led to the creation of the Viceroyalty of New Granada (comprising modern-day Colombia, Venezuela, Ecuador and Panama) with its capital at Bogotá. Independence from Spain was won in 1819, but by 1830 "Gran Colombia" had collapsed with the secession of Venezuela and Ecuador. What is now Colombia and Panama emerged as the Republic of New Granada. The new nation experimented with federalism as the Granadine Confederation (1858), and then the United States of Colombia (1863), before the Republic of Colombia was finally declared in 1886.Panama seceded in 1903.

Colombia has a long tradition of constitutional government, and the Liberal and Conservative parties, founded in 1848 and 1849 respectively, are two of the oldest surviving political parties in the Americas. However, tensions between the two have frequently erupted into violence, most notably in the Thousand Days War (1899-1902) and La Violencia, beginning in 1948. Since the 1960s, government forces, left-wing insurgents and right-wing paramilitaries have been engaged in the continent's longest-running armed conflict. Fuelled by the cocaine trade, this escalated dramatically in the 1990s. However, the insurgents lack the military or popular support necessary to overthrow the government, and in recent years the violence has been decreasing. Many paramilitary groups have demobilized as part of a controversial peace process with the government, and the guerrillas have lost control in many areas where they once dominated. Meanwhile Colombia's homicide rate, for many years the highest in the world, has almost halved since 2002.

Colombia is a standing middle power with the fourth largest economy in South America. It is very ethnically diverse, and the interaction between descendants of the original native inhabitants, Spanish colonists, African slaves and twentieth-century immigrants from Europe and the Middle East has produced a rich cultural heritage. This has also been influenced by Colombia's varied geography. The majority of the urban centres are located in the highlands of the Andes mountains, but Colombian territory also encompasses Amazon rainforest, tropical grassland and both Caribbean and Pacific coastlines. Ecologically, Colombia is one of the world's 18 megadiverse countries.