Ecuador straddles the equator, from which it takes its name, and has an area of 283.561 km2, 109,415 sq ml. Its capital city is Quito, which was declared a World Heritage Site by UNESCO in the 1970s for having the best preserved and least altered historic center in Latin America. The country's largest city is Guayaquil. The historic center of Cuenca, the third largest city in the country, was also declared a World Heritage Site in 1999, for being an outstanding example of a planned inland Spanish style colonial city in the Americas. Ecuador is also home—despite its size—to a great variety of species, many of them endemic, like those of the Galápagos islands. This species diversity makes Ecuador one of the seventeen megadiverse countries in the world. The new constitution of 2008 is the first in the world to recognize legally enforceable Rights of Nature, or ecosystem rights.

Ecuador is a presidential republic and became independent in 1830, after having been part of the Spanish colonial empire and the republic of Gran Colombia. It is a medium-income country with an HDI score of 1.025 (2010), and about 35.1% of the people living below the poverty line.

Evidence of human cultures in Ecuador exists from c. 3500 B.C. Many civilizations rose throughout Ecuador, such as the Valdivia Culture and Machalilla Culture on the coast, the Quitus (near present day Quito) and the Cañari (near present day Cuenca). Each civilization developed its own distinctive architecture, pottery, and religious interests, although consolidated under a confederation called the Shyris which exercised organized trading and bartering between the different regions and whose political and military power was under the rule of the Duchicela blood line before the Inca invasion. After years of fiery resistance by the Cañaris and other tribes, as demonstrated by the battle of Yahuarcocha (Blood Lake) where thousands of resistance fighters were killed and thrown in the lake, the region fell to the Incan expansion and was assimilated loosely into the Incan empire.

Through a succession of wars and marriages among the nations that inhabited the valley, the region became part of the Inca Empire in 1463. When the Spanish conquistadors arrived from the north, the Inca Empire was ruled by Huayna Capac, who had two sons: Atahualpa, being in charge of the northern parts of the empire, and Huascar, seated in the Incan capital Cusco. Upon Huayna Capac's death in 1525, the empire was divided in two: Atahualpa received the north, with his capital in Quito; Huascar received the south, with its capital in Cusco. In 1530, Atahualpa defeated Huascar and conquered the entire empire.

Disease decimated the indigenous population during the first decades of Spanish rule — a time when the natives also were forced into the encomienda labor system for Spanish landlords. In 1563, Quito became the seat of a real audiencia (administrative district) of Spain and part of the Vice-Royalty of Lima, and later the Vice-Royalty of Nueva Granada.

After nearly 300 years of Spanish colonization, Quito was still a small city of only 10,000 inhabitants. It was there, on August 10, 1809 (the national holiday), that the first call for independence from Spain was made in Latin America ("Primer Grito de la Independencia"), under the leadership of the city's criollos like Juan Pío Montúfar, Quiroga, Salinas, and Bishop Cuero y Caicedo. Quito's nickname, "Luz de América" ("Light of America"), comes from the fact that it was the first successful attempt to produce an independent and local government, although for no more than two months, that had an important repercussion and inspiration for the emancipation of the rest of Spanish America. Quito is also known as "La Cara de Dios" ("The Face of God") for the beauty of its religious colonial art and architecture cloistered in the amazing equatorial Andes landscape.

On October 9, 1820, Guayaquil became the first city in Ecuador to gain its independence from Spain. On May 24, 1822, the rest of Ecuador gained its independence after Antonio José de Sucre defeated the Spanish Royalist forces at the Battle of Pichincha, near Quito. Following the battle, Ecuador joined Simón Bolívar's Republic of Gran Colombia - joining with modern day Colombia and Venezuela – only to become a republic in 1830.

The 19th century for Ecuador was marked by instability, with a rapid succession of rulers. The first president of Ecuador was the Venezuelan-born Juan José Flores, who was ultimately deposed, followed by many authoritarian leaders such as Vicente Rocafuerte; José Joaquín de Olmedo; José María Urbina; Diego Noboa; Pedro José de Arteta; Manuel de Ascásubi; and Flores's own son, Antonio Flores Jijón, among others. The conservative Gabriel Garcia Moreno unified the country in the 1860s with the support of the Roman Catholic Church. In the late 19th century, world demand for cocoa tied the economy to commodity exports and led to migrations from the highlands to the agricultural frontier on the coast.

The coast-based Liberal Revolution of 1895 under Eloy Alfaro reduced the power of the clergy and the conservative land owners of the highlands, and this liberal wing retained power until the military "Julian Revolution" of 1925. The 1930s and 1940s were marked by instability and emergence of populist politicians, such as five-time President José María Velasco Ibarra.

Control over territory in the Amazon basin led to a long-lasting dispute between Ecuador and Peru. In 1941, amid fast-growing tensions between the two countries, war broke out. Peru claimed that Ecuador's military presence in Peruvian-claimed territory was an invasion; Ecuador, for its part, claimed that Peru had invaded Ecuador. In July 1941, troops were mobilized in both countries. Peru had an army of 11,681 troops who faced a poorly supplied and inadequately armed Ecuadorian force of 2,300, of which only 1,300 were deployed in the southern provinces. Hostilities erupted on July 5, 1941, when Peruvian forces crossed the Zarumilla river at several locations, testing the strength and resolve of the Ecuadorian border troops. Finally, on July 23, 1941, the Peruvians launched a major invasion, crossing the Zarumilla river in force and advancing into the Ecuadorian province of El Oro.