Syntax: Syntax refers to the rules for combining words into grammatically sensible sentences in a given language.
Pragmatics: Pragmatics is concerned with the use of language in social contexts and the ways people produce and comprehend meanings through language.
Morphemes: Morphemes are the smallest meaningful units of language. They can be whole words (like "a" or "run") or parts of words (like "-ed" which indicates past tense).