Typology is the classification of languages by grammatical features. Typological classification contrasts with the more familiar genetic classification of languages into families that share an ancestor language (see historical linguistics). A genetic class is a language family, while a typological class is a language type.
One set of types sometimes called just the "typology" of a language is the order of the subject, the verb, and the object:
- Subject Verb Object
- Subject Object Verb
- Verb Subject Object
- Verb Object Subject
- Object Subject Verb
- Object Verb Subject
Some languages split verbs into an auxiliary and an infinitive or participle, and put the subject or object between them. For instance, German ("Im Wald habe ich einen Fuchs gesehen" - "In-the wood have I a fox seen") and Welsh ("Mae'r gwirio sillafu wedi'i gwblhau" - "Is the check spelling after to complete"). In this case, typology is based on the non-analytic tenses (i.e. those sentences in which the verb is not split) or the position of the auxiliary. German is thus SVO/VSO (without "im Wald" the subject would go first) in main clauses and Welsh is VSO (and O would go after the infinitive).
Another common classification is whether the language is ergative or accusative. If the language has casess, this is determined by whether the subject of an intransitive verb has the same case as the subject or the object of a transitive verb. If it doesn't, but the order is SVO or OVS, this is determined by whether the subject of the intransitive verb is on the same side as the subject or the object of the transitive verb.
In many cases a language shows mixed accusative and ergative behaviour (e. g. ergative morphology marking the verb arguments, on top of an accusative syntax), or behaves ergatively only in some contexts (this is called split ergativity, and is usually based on the grammatical person of the arguments or in the tense/aspect of the verb).