Proto-Indo-European is believed to be the ancestor of many modern languages spoken in Europe, Asia, and parts of the Americas.

Language acquisition refers to the natural process by which humans learn to understand and produce language.

Noam Chomsky's theory of universal grammar suggests that all human languages share certain fundamental principles.

The mental lexicon is the store of words and their meanings in the mind.

Cognitive biases are systematic errors in thinking that occur when people make judgments and decisions.

Language competence refers to the underlying knowledge of language rules and structures.

Transformational grammar is a type of generative grammar that describes how sentences are formed from underlying structures.

Psycholinguistics is the study of the psychological processes involved in language comprehension and production.

Language universals are features that are common to all human languages.

Sociolinguistics is the study of the relationship between language and social factors such as class, gender, and ethnicity.

Speech acts are actions that are performed through language.

Cultural linguistics, anthropological linguistics, and ethnolinguistics are all fields that study the relationship between language and culture.

Language games are activities that involve the use of language.

Critical linguistics is the study of the relationship between language and power.

Language ideologies are beliefs about language that are shared by a group of people.