Editing Grammatical case (section)

===Morphosyntactic alignment===
{{main|Morphosyntactic alignment}}

Languages are categorized into several case systems, based on their ''morphosyntactic alignment''—how they group verb [[agent (linguistics)|agents]] and [[patient (linguistics)|patients]] into cases:

* ''[[nominative–accusative language|Nominative–accusative]]'' (or simply ''accusative''): The argument (subject) of an intransitive verb is in the same case as the agent (subject) of a transitive verb; this case is then called the ''[[nominative case]]'', with the patient (direct object) of a transitive verb being in the ''[[accusative case]]''.
* ''[[ergative–absolutive language|Ergative–absolutive]]'' (or simply ''ergative''): The argument (subject) of an intransitive verb is in the same case as the patient (direct object) of a transitive verb; this case is then called the ''[[absolutive case]]'', with the agent (subject) of a transitive verb being in the ''[[ergative case]]''.
* ''[[ergative–accusative language|Ergative–accusative]]'' (or ''tripartite''): The argument (subject) of an intransitive verb is in its own case (the ''[[intransitive case]]''), separate from that of the agent (subject) or patient (direct object) of a transitive verb (which is in the ergative case or accusative case, respectively).
* ''[[active–stative language|Active–stative]]'' (or simply ''active''): The argument (subject) of an intransitive verb can be in one of two cases; if the argument is an ''agent'', as in "He ate", then it is in the same case as the agent (subject) of a transitive verb (sometimes called the ''agentive case''), and if it is a ''patient'', as in "He tripped", then it is in the same case as the patient (direct object) of a transitive verb (sometimes called the ''patientive case'').
* ''[[trigger language|Trigger]]'': One noun in a sentence is the topic or focus. This noun is in the [[trigger case]], and information elsewhere in the sentence (for example a [[verb]] [[affix]] in [[Tagalog language|Tagalog]]) specifies the role of the trigger. The trigger may be identified as the agent, patient, etc. Other nouns may be inflected for case, but the inflections are overloaded; for example, in Tagalog, the subject and object of a verb are both expressed in the [[genitive case]] when they are not in the trigger case.

The following are systems that some languages use to mark case instead of, or in addition to, declension:
* '''Positional''': Nouns are not inflected for case; the position of a noun in the sentence expresses its case.
* [[Adposition]]al: Nouns are accompanied by words that mark case.