Most would concur that the English language possess but three cases: subjective, objective, and possessive. Though popular today, misinformation should be distrusted. In this case, folly reigns supreme as chief grammatical practice, and the progressive education model continues not only to dilate its pockets with the coin of the dunderheaded, but also relies on teachers of foreign languages to teach English case.
English, however, retains the Latin cases.
Nominative: the naming case. Most readily known as the subjective case. The nominative case identifies the subject of a sentence (The soldier fainted during the ceremony) as well as any pronouns or adjectives in that sentence grammatically related to that same subject (The tall soldier, who fainted at the ceremony, he…).
Vocative: the calling case. Though similar in appearance to the nominative, the vocative case, as Kingsley Amis writes in his style guide, The King’s English, is “used when addressing or invoking some person or abstraction.” Hamlet has the abstraction bit down: “Frailty, thy name is woman.” Or, for more everyday sort of talk: “It’s been nice talking with you, Jim.” Hamlet could have eased things up with a simple “women are frail” and “Jim” could have stopped with “you,” but that wouldn’t have called them out.
Accusative: the picking-out case. Here, the nouns and accompanied verbiage therein form what’s commonly understood as the direct object, the object of a sentence at which the subject aims with a transitive verb (King Henry VIII beheaded Sir Thomas Moore…Jane threw the ball).
Dative: the giving case. “Corresponding with to or for,” the dative expresses recipience. In “Jane threw Jack the ball,” Jack is in the dative case, as he is the recipient of this highly sought-after ball. This means the same thing as “Jane threw the ball to Jack,” except that “to Jack” is not in the dative, but rather a part of a prepositional phrase, which means that we’re now also sans indirect object.
Genitive, the ownership or source case, corresponding with of or from. Many will recognize the possessive’s apostrophe-s form: “the gods’/god’s ambrosia,” as stand-in for “the ambrosia of the gods/god.”
Ablative, the case that corresponds to source or cause. We often see this in the passive voice: “The pugilist’s insides were explored by his opponent.” Or, “The waltz came from Austria.”
In addition to honest, stand-up instructional failure, English’s absence of inflection is likely partly to blame for the general notion of English’s contemporary existence as merely a tenuously linked series of case-less, primordial grunts.
An inflection is a change in the form of a word to denote tense, mood, person, number, case, and/or gender. This is clearer in other languages such as German or French, whose word-endings alter to denote what English does invisibly. Declensions and conjugations are two examples, or in this case, case.