Syntax is the system of rules governing how words combine to form phrases, clauses, and sentences. It determines that The cat sat on the mat is English but Cat the on sat mat the is not. Where morphology operates within the word, syntax operates between words.
Phrase structure: sentences are not flat strings of words but hierarchical trees. A sentence (S) divides into a noun phrase (NP) and a verb phrase (VP), which in turn contain determiners, heads, complements, and modifiers. Chomsky's phrase structure rules (1957, 1965) formalized this hierarchy.
Word order typology: languages differ systematically in the default order of Subject, Verb, and Object. English is SVO; Japanese is SOV; Arabic is VSO. Greenberg (1963) identified word-order universals and their correlations (e.g., SVO languages tend to use prepositions; SOV languages tend to use postpositions).
Constituency: words group into constituents that function as units. Tests for constituency include movement (It was on the mat that the cat sat), substitution (The cat sat there), and coordination (on the mat and under the table).
Dependency: an alternative view (Tesnière, 1959) treats syntax as a network of dependencies between a head word and its dependents, rather than as nested phrases. Dependency grammar is widely used in computational linguistics and corpus analysis.
Syntax is implicitly present in every grammar lesson, though the term itself is rarely used in the classroom. Key teaching connections: