Nativism, particularly as proposed by Noam Chomsky, posits that humans possess an innate capacity for language acquisition, including a universal grammar that underlies all languages.

In generative grammar, the deep structure is the underlying abstract representation of a sentence, which is transformed into the surface structure through a series of rules.

Functional Grammar, developed by Simon Dik, focuses on the role of functional categories, such as subject, object, and verb, and their interaction in determining sentence structure.

Semantics is the study of meaning in language, including the meaning of words, phrases, and sentences.

Pragmatics is the study of how language is used in context, including the role of speaker intention, context, and shared knowledge in understanding language.

Discourse Analysis is the study of how language is used in social interaction, including the structure and organization of conversations, narratives, and other forms of discourse.

Interactionism, as proposed by Lev Vygotsky, emphasizes the role of social interaction and language input in language learning, suggesting that children learn language through their interactions with others.

Syntax is the study of how words are combined into phrases and sentences, including the rules and principles that govern sentence structure.

Constructivism, as proposed by Jean Piaget, emphasizes the role of active construction and hypothesis testing in language learning, suggesting that children actively construct their understanding of language through their interactions with the environment.

Sociolinguistics is the study of how language varies across different social and cultural contexts, including the relationship between language and social factors such as class, gender, and ethnicity.

Cognitive Grammar, developed by Ronald Langacker, emphasizes the role of cognitive processes in language comprehension and production, suggesting that language is a conceptual system that reflects our understanding of the world.

Neurolinguistics is the study of how language is processed in the brain, including the neural mechanisms involved in language comprehension, production, and acquisition.

Usage-Based Theory, as proposed by Michael Tomasello, emphasizes the role of usage-based learning and the gradual accumulation of linguistic knowledge through exposure to language input.

Computational Linguistics is the study of how computers can understand and generate human language, including the development of natural language processing systems and machine translation.

Construction Grammar, developed by Charles Fillmore and others, emphasizes the role of constructions, or pre-packaged units of language, in language comprehension and production.