In Pre-Columbian Mesoamerica many cultures matured into advanced civilizations such as the Olmec, the Toltec, the Teotihuacan, the Zapotec, the Maya and the Aztec before the first contact with Europeans. In 1521, Spain conquered and colonized the territory, which was administered as the viceroyalty of New Spain which would eventually become Mexico as the colony gained independence in 1821. The post-independence period was characterized by economic instability, territorial secession and civil war, including foreign intervention, two empires and two long domestic dictatorships. The latter led to the Mexican Revolution in 1910, which culminated with the promulgation of the 1917 Constitution and the emergence of the country's current political system. Elections held in July 2000 marked the first time that an opposition party won the presidency from the Institutional Revolutionary Party (Spanish: Partido Revolucionario Institucional, PRI).

As a regional power, and since 1994 the first Latin American member of the Organisation for Economic Co-operation and Development (OECD), Mexico is firmly established as an upper middle-income country, and is considered a newly industrialized country and an emerging power. It has the 13th largest nominal GDP and the 11th largest by purchasing power parity. The economy is strongly linked to those of its North American Free Trade Agreement (NAFTA) partners, especially the United States, as well as tourism, being the world's tenth most visited country with over 21.4 million international arrivals. Mexico boasts a long tradition in the arts, renowned cuisine, and culture, and it ranks fifth in the world and first in the Americas on the list of UNESCO World Heritage Sites with 31.

After New Spain won independence from Spain, it was decided that the new country would be named after its capital, Mexico City, which was founded in 1524 on top of the ancient Aztec capital of México-Tenochtitlan. The name comes from the Nahuatl language, but its meaning is not known. It has been suggested that it is derived from Mextli or Mēxihtli, a secret name for the god of war and patron of the Aztecs, Huitzilopochtli, in which case Mēxihco means "Place where Mēxihtli lives".

Another hypothesis suggests that the word Mēxihco derives from the mētztli ("moon"), xictli ("navel", "center" or "son"), and the suffix -co (place), in which case it means "Place at the center of the moon" or "Place at the center of the Lake Moon", in reference to Lake Texcoco. The system of interconnected lakes, of which Texcoco was at the center, had the form of a rabbit, the same image that the Aztecs saw in the moon. Tenochtitlan was located at the center (or navel) of the lake (or rabbit/moon). Still another hypothesis suggests that it is derived from Mēctli, the goddess of maguey.

The name of the city was transliterated to Spanish as México with the phonetic value of the x in Medieval Spanish, which represented the voiceless postalveolar fricative /ʃ/. This sound, as well as the voiced postalveolar fricative /ʒ/, represented by a j, evolved into a voiceless velar fricative /x/ during the sixteenth century. This led to the use of the variant Méjico in many publications in Spanish, most notably in Spain, whereas in Mexico and most other Spanish–speaking countries México was the preferred spelling. In recent years the Real Academia Española, which regulates the Spanish language, determined that both variants are acceptable in Spanish but that the normative recommended spelling is México. The majority of publications in all Spanish-speaking countries now adhere to the new norm, even though the alternative variant is still occasionally used. In English, the x in Mexico represents neither the original nor the current sound, but the consonant cluster /ks/.

The official name of the country has changed as the form of government has changed. On two occasions (1821–1823 and 1863–1867), the country was known as Imperio Mexicano (Mexican Empire). All three federal constitutions (1824, 1857 and 1917, the current constitution) used the name Estados Unidos Mexicanos—or the variants Estados Unidos mexicanos and Estados-Unidos Mexicanos, all of which have been translated as "United Mexican States". The term República Mexicana, "Mexican Republic" was used in the 1836 Constitutional Laws.

Campfire remains in the Valley of Mexico have been radiocarbon-dated to 21,000 BCE, and a few chips of stone tools have been found near the hearths, indicating the presence of humans at that time. Around 9,000 years ago, ancient indigenous peoples domesticated corn and initiated an agricultural revolution, leading to the formation of many complex civilizations. Between 1,800 and 300 BCE, many matured into advanced pre-Columbian Mesoamerican civilizations such as: the Olmec, the Teotihuacan, the Maya, the Zapotec, the Mixtec, the Toltec and the Aztec, which flourished for nearly 4,000 years before the first contact with Europeans.

These civilizations are credited with many inventions and advancements in fields such as architecture (pyramid-temples), mathematics, astronomy, medicine and theology. The Aztecs were noted for practicing human sacrifice on a large scale. At its peak, Teotihuacan, containing some of the largest pyramidal structures built in the pre-Columbian Americas, had a population of more than 150,000 people. Estimates of the population before the Spanish conquest range from 6 million to 25 million.

In the early 16th century, from the landing of Hernán Cortés, the Aztec civilization was invaded and conquered by the Spaniards. Unintentionally introduced by Spanish conquerors, smallpox ravaged Mesoamerica in the 1520s, killing millions of Aztecs, including the emperor, and was credited with the victory of Hernán Cortés over the Aztec empire. The territory became part of the Spanish Empire under the name of New Spain. Much of the identity, traditions and architecture of Mexico were created during the colonial period.

On September 16, 1810, independence from Spain was declared by priest Miguel Hidalgo y Costilla, in the small town of Dolores, Guanajuato. The first insurgent group was formed by Hidalgo, the Spanish viceregal army captain Ignacio Allende, the militia captain Juan Aldama and "La Corregidora" Josefa Ortiz de Domínguez. Hidalgo and some of his soldiers were captured and executed by firing squad in Chihuahua, on July 31, 1811. Following his death, the leadership was assumed by priest José María Morelos, who occupied key southern cities.