If we want to master Croatian, we have to deal with seven (that's right ... 🙀 seven ...) cases.
Let's get an overview over those seven cases and their functions within a Croatian sentence.

First case:
Nominative (abbr. N, hr. nominativ)

The subject of every Croatian sentence stands in the nominative case.
If you want to find the subject of a Croatian sentence, you use the interrogative pronouns tko? (who?) or što? (what?).
 
💡 For example:
Tko poklanja svojoj prijateljici Ani cvijeće?
Who gives flowers to his friend Ana?
Petar poklanja svojoj prijateljici Ani cvijeće.
Petar gives flowers to his friend Ana.

Second case:
Genitive (abbr. G, hr. genitiv) – is used in a wider range than in English!

If you want to discover a genitive form in a Croatian sentence, you ask: koga? (whose?, when related to a person) or čega? (whose?, when related to things)
The genitive in Croatian describes relations – like ownership, temporal relations, spatial distances.
We also use the genitive in Croatian when we talk about quantity and numbers of persons or things.
The genitive is used to describe the origin of persons or things.
Also certain expression of time only want to be seen and heard together with the genitive.
Some Croatian prepositions demand to be combined together a genitive form.
Some examples for prepositions that have to be used together with a genitive form: bez, do, ispod, iz, iza, iznad, kod, od, po, pored, preko, prije, protiv – and many more.
 
💡 For example:
Ovo je cvijeće Anine sestre. - These are the flowers of Ana's sister.
Ona živi razdvojeno od obitelji. - She lives separated from her family.

Third case:
Dative (abbr. D, hr. dativ)

If you analyse a Croatian sentence and you want find out where the dative form is hiding, you ask: komu? (whom?, when the noun in the dative is animated) or čemu? (whom?, when the noun in the dative form is inanimated).
The function of the dative in a Croatian sentence is to mark the indirect object.
Some Croatian verbs are always followed by the noun in dative, e.g.: dati, darovati, reći, kupiti, napisati, poslati, požaliti se.
Also you need to get acquainted with Croatian prepositions that ask for the usage of the dative: k, ka, nadomak, nasuprot, prema, unatoč, uprkos
 
💡 For example:
Petar poklanja svojoj prijateljici Ani cvijeće.
Petar gives flowers to his friend Ana.

Fourth case:
Accusative (abbr. A, hr. akuzativ)

If you are searching for the accusative in a Croatian sentence, you ask: Koga? (who?, when the noun in the accusative is animated) or Čega? (what?, when the noun in the accusative form is inanimated).
The function of the accusative in a Croatian sentence is to mark the direct object.
The accusative is often used together with verbs that signalize a movement.
For example: baciti, donijeti, juriti, voziti se
Some Croatian prepositions call for the use of the accusative, e.g.: kroz, među, na, nad, niz, o, po, pod, pred, u, za
 
💡 For example:
Petar poklanja svojoj prijateljici Ani cvijeće.
Petar gives flowers to his friend Ana.

Fifth case:
Locative (abbr. L, hr lokativ) – please remember: the locative in Croatian always comes with a preposition!

If you try to track down a noun in the locative in a Croatian sentence, you ask: Gdje? (where?) or O čemu? (where of?).
A Croatian noun with a locative ending describes the whereabouts or the location of a person or an object.
To give you a hint on how to make learning the case endings more easy: The dative and locative endings are similar.
You will find the noun with its locative ending after the following prepositions: na, o, po, u pri.
 
💡 For example:
Anino cvijeće stoji na stolu. Ana's flowers are on the table.

Sixth case:
Instrumental (abbr. I, hr. instrumental)

With the help of these question words, you can identify Croatian nouns with instrumental endings: S kim? (with whom?) or Čime? (with what?).
Please, try to get acquainted with this new case ending.
The English language doesn't posses a case like this.
With the instrumental case Croatian describes the means or the device with which an action is executed.
These prepositions stand together with instrumental case endings: među, nad (a), pod (a), pred, s(a), za
 
💡 For example:
Ana reže cvijeće nožem.
Ana cuts the flowers with a knife.

Seventh case:
Vocative (abbr. V, hr. vokativ) – another new case that we have to meet!

We find vocative case endings in Croatian whenever we want to address another person.
 
💡 For example:
Ana, donio sam ti cvijeće.
Ana, I have brought you flowers.