Nahuatl belongs to the Uto-Aztecan family, related to languages such as Hopi, Cora, and Huichol. Its speakers, the Nahuas, reached central Mexico from the north in migratory waves between the 6th and 13th centuries. Classical Nahuatl was the lingua franca of the Mexica (Aztec) empire centered on Mēxihco-Tenochtitlan.

Today Nahuatl is the most widely spoken Indigenous language in Mexico, with around 1.65 million speakers. It is spoken in Puebla, Veracruz, Hidalgo, Guerrero, San Luis Potosí, the State of Mexico, and other regions, in many varieties. Nahua culture preserves the milpa, festivals of the agricultural cycle, and a rich oral tradition of songs and counsel (huēhuehtlahtōlli).

After the 1521 conquest, friars adapted the Latin alphabet to write Nahuatl and produced grammars, vocabularies, and chronicles, such as the work of fray Bernardino de Sahagún (the Florentine Codex). Nahuatl served as an administrative and evangelizing language through much of the colonial period, leaving an enormous corpus of Nahuatl-language documents.

Despite its number of speakers, Nahuatl is classified as vulnerable due to pressure from Spanish. The General Law of Linguistic Rights (2003) recognizes Nahuatl as a national language, and INALI promotes writing standards. Intercultural bilingual education, contemporary literature, music, and a growing digital presence are driving its revitalization.