Universal Grammar (UG): An innate, biological blueprint of grammatical principles shared by all human languages.
Language Acquisition Device (LAD): A theoretical "mental organ" or "black box" in the brain that allows children to trigger language rules from input.
Poverty of the Stimulus: The argument that children acquire language skills far beyond the limited and messy input they receive from adults.
Competence vs. Performance: Competence is the intuitive knowledge of language rules; Performance is the actual use of language in real situations.
Critical Period Hypothesis (CPH): The theory that there is a biological window (ending around puberty) after which native-like language acquisition is much more difficult.
