Vocative Case

Answers the questions who or what are you calling - or to call someone from a distance. This case is rarely used and some say don't even bother to learn it... who am I to argue? However, there are uses that are common:

• when using titles - very important in Polish society - the Vocative is obligatory: Dzień dobry, panie profesorze! (Hello, professsor-Voc.!)
• with diminutive (affectionate) forms of first names: Kasiu! Grzesiu! Hanu!

Locative Case

Case of location - answers the questions 'Who am I talking about?' (o kim?) I am talking about the movie star - and 'What am I talking about?' (o czym?) - and What is it on? On the plane, On the street, In the building. Note that it is only used after the prepositions:

• na 'on, at'
• w 'in'
• po 'about, along'
• przy 'near, by'
• o 'concerning'

Instrumental Case

Generally related to the English preposition 'with' or 'by' when referring to transportation.

Answers the questions-whom am I doing something with? With what am I doing something with? I am talking on the phone with Joseph. I am traveling by train. This is also a case of location, most commonly used with "Z" or with." also Przed-in front of Nad-above Pod-under, bellow Za- behind.

Dative Case

The indirect object (always the person to whom something happens or is given: she gave me her address).

Also used after four prepositions:

• dzięki (thanks to)
• wbrew (contrary to, against)
• ku (to, toward)
• przeciw/ko (against)

Accusative Case

The direct object of most verbs; the object of some prepositions.

Answers the questions: What is the action is about? Whom the action is about? I see the tree. I see what? The tree. I see Mark. I see who? Mark. We would like to visit Krakow . What would you like to visit? Krakow . I have a new dress. What do you have? A new dress.

Most common verbs used: I see, I have, I like.

Other examples: I am going to buy a plane ticket. I am going to buy what? A plane ticket. I am going to sell my car. I am going to sell what? My car.

The accusative also follows preposition that indicate going towards or motion. Pzez-through Na-on, to, towards, for I am going to the market. I am waiting for my love. I will be on vacation. I am walking through the building.

Incidentally, the most common Polish cases are the nominative (dictionary form) and accusative, which account for almost 65% of the Polish cases. The nominative, accusative, genitive, and locative accounts for over 90% of the Polish cases. But you still have to learn them all :-)

Genitive Case

The case that marks a noun as being the possessor of another noun (which is why it's also widely known as the possessive case). Thus "Danuta's brother" is brat Danuty (or Danuty brat) and "father's automobile" is samochód ojca (or ojca samochód).

In Polish, the genitive is also used:

• with direct object after a negated verb (thus Mam klucz (I have a key) with the accusative is negated as Nie mam klucza (I don't have a key) with the genitive).
• after words naming quantity or measure (corresponds to of in English: szklanka herbaty (a glass of tea), dużo czasu (a lot of time).
• after certain verbs, such as: potrzebować (to need), słuchać (to listen to ), szukać (to look for), uczyć (to teach), uczyć się (to study, learn), używać (to use).
• Cardinal Numbers from 5-21, 25-31, 35-41, 45-51, etc... are followed by the genitive plural (thus Zyzio ma sześć lat, Tomasz ma piętnaście samochodów).
• Finally, genitive is used with a wide range of prepositions. Several express the starting point of moton: z domu (out of the house), z koncertu (from the concert), od Danuty (from Danuta). Other prepositions requiring the genitive case are u (by, in the presence of), do (to, into), dla (for, on behalf of), and bez (without).

Via Frank Y. Gladney's excellent Elementary Polish

Nominative Case

Subject of the sentence.

Answers the questions: What is it? Who is it? It is a Park. What is it? a park. It is Mark. Who is it? Mark. The park is green. What is green? the park. The man is walking. Who is walking? the man.

Usually used with the verb "to be"

This is the case that simply names the entity in question and does not mark its dependence on any other word in the sentence. It is the case of the subject of the sentence.

In English, the role a noun plays in the sentence is indicated mainly by its position. When we hear Stan loves Barb we recognize Stan as the subject of the sentence (the source of the affection) and Barb as its object (the direct object of the sentence). In Barb loves Stan the different word order assigns different sentence roles to the two nouns.

In Polish, where "Stan" is Staś-, "loves" is kocha, and "Barb" is Baś-, it is CASE that communicates who loves whom. Case is indicated by the noun's case ending. NOMINATIVE case, which is indicated by a nominative-case ending (let us represent it as NOM), marks the subject of the sentence. ACCUSATIVE case, which is indicated by a accusative-case ending (let us represent it as ACC), marks the direct object of the sentence. So "Stan loves Barb" may be represented as Staś-NOM kocha Baś-ACC, and "Barb loves Stan" may be represented as Baś-NOM kocha Staś-ACC

(source)

Polskie Cases Overview

This is going to be my starting point, as this is probably where I have the most difficulty. Thing is, nouns and adjectives change their endings in singular and plural according to the way they're used as either subject or object or even if they're used with a particular preposition, verb or prepositional phrase (whatver that is) - and I just NEVER know when to '-ego' and when to '-ą' or '-ę'...

Anyway, there are seven cases to squeeze into your head - count 'em, here presented in their traditional order:

• Nominative (mianownik)
• Genitive (dopełniacz)
• Dative (celownik)
• Accusative (biernik)
• Instrumental (narzędnik)
• Locative (miejscownik)
• Vocative (wołacz)

The following posts will all be a more in-depth presentation of each case, with not too much text but hopefully-helpful links (uczmy się polskiego on the right of here), useful guidance and exercises (100 Exercises on Cases!) plus a mind map like the one here (just click on it for a larger version):