Latin Nouns

Five declensions: Latin nouns are divided into five groups called declensions: first declension, second declension....

Cases: In Latin's mother language, Proto-Indo-European (PIE), nouns could interact with verbs in eight ways. Each way was called case.

Nominative/Subjective:   He walked the dog.
Genitive/Possessive:        His idea was ridiculous.
Accusative/Objective:      I smacked him.
Dative:                              It was an interesting day for him.

Ablative:                          This bookcase was built by him.
Instrumental:                   We went to Rome with him.
Locative:                          A bug was crawling on him.
Vocative:                         Dude!

In Latin, the ablative case absorbed the instrumental and locative cases.