In Latin, nouns have to undergo declension. Declension of nouns are necessary to show whether a sentence is plural or singular, feminine or masculine etc. Latin declensions of nouns consist of six grammatical casus or cases:

1) Nominative – marks the subject of a sentence. It answers the question: who? or what? The subject is usually followed by a linking verb like to be.

2) Genitive – expresses possession. It answers the question: whose?

3) Dative – marks the recipient of an action. It answers the question: for who does something exist, benefit, disadvantage, etc.

4) Accusative – marks the direct object of the verb. For example in English, the direct object of the sentence I feed the dog is the dog.

5) Ablative – indicates the means by which an action is performed. In English, the prepositions by, with, and from serve this purpose.

6) Vocative – is not used as much as the other casus or cases are used. The vocative is used to address someone in direct speech. For example if you were to call someone out by saying, Hey You! The you would be the vocative. Some Latin grammar books don’t even bother to list the vocative. They just lump the vocative with the nominative.

7) Locative – I hestitated to list the locative, since it’s rarely used, but just in case you come across it, it’s just used to express the place in which an action is performed. It’s kind of like the preposition at or in.  For example the locative in the sentence We live in Rome would be in Rome. Don’t worry too much about the locative. The other six are the ones you should focus on.