Most people acquire at least one language without formal lessons. A first language is the language or languages a person learns from earliest childhood through immersion in a speech community, often called a native language or mother tongue.

First-language acquisition follows broadly shared developmental milestones while reflecting the specific grammar being learned. Phonology, vocabulary, and complex syntax emerge in overlapping stages. Children may grow up with two first languages in truly bilingual homes.

First-language proficiency typically remains dominant for emotion and rapid processing, though life circumstances can shift dominance. Education systems built on a child’s first language support learning across subjects. The term identifies order and early environment of acquisition rather than permanent superiority of skill.

• Language acquired from earliest childhood
• Learned through immersion rather than formal study alone
• May be more than one in bilingual settings
• Shapes identity and often remains dominant