Japanese is an agglutinative, synthetic, mora-timed language with simple phonotactics, a pure vowel system, phonemic vowel and consonant length, and a lexically significant pitch-accent. Word order is normally subject–object–verb with particles marking the grammatical function of words, and sentence structure is topic–comment. Its phrases are exclusively head-final and compound sentences are exclusively left-branching. Sentence-final particles are used to add emotional or emphatic impact, or make questions. Nouns have no grammatical number or gender, and there are no articles. Verbs are conjugated, primarily for tense and voice, but not person. Japanese adjectives are also conjugated. Japanese has a complex system of honorifics with verb forms and vocabulary to indicate the relative status of the speaker, the listener, and persons mentioned.
In language typology, it has many features different from most European languages.
The modern theory of constituent order ("word order"), usually attributed to Joseph Harold Greenberg, identifies several kinds of phrases. Each one has a head and possibly a modifier. The head of a phrase either precedes its modifier (head-initial) or follows it (head-final). Some of these phrase types, with the head marked in boldface, are:
genitive phrase, i.e., noun modified by another noun ("the cover of the book", "the book's cover");
noun governed by an adposition ("on the table", "underneath the table");
comparison ("[X is] bigger than Y", i.e., "compared to Y, X is big").
noun modified by an adjective ("black cat").
Some languages are inconsistent in constituent order, having a mixture of head-initial phrase types and head-final phrase types. Looking at the preceding list, English for example is mostly head-initial, but nouns follow the adjectives which modify them. Moreover, genitive phrases can be either head-initial or head-final in English. By contrast, the Japanese language is consistently head-final:
genitive phrase:
noun governed by an adposition:
comparison:
noun modified by an adjective:
Head-finality in Japanese sentence structure carries over to the building of sentences using other sentences.