Typology is a subfield of linguistics that studies and classifies languages according to their structural features.
One set of types reflects the basic order of subject, verb, and direct object in sentences:
- Subject-verb-object
- Subject-object-verb
- Verb-subject-object
- Verb-object-subject
- Object-subject-verb
- Object-verb-subject
Another common classification distinguishes nominative-accusative languages and ergative-absolutive ones. In a language with cases, the classification depends on whether the subject of an intransitive verb has the same case as the agent or the patient of a transitive verb. If a language has no cases, but the word order AVP or PVA, then a classification may reflect whether the subject of an intransitive verb appears on the same side as the agent or the patient of the transitive verb.