Most grammars of Turkish consider there to be six cases: nominative, accusative, genitive, dative, locative, ablative.
The nominative - used for subjects (and also for INDEFINITE objects) - takes no ending. Exx. "Çocuk yiyor." - "The child is eating." "Kedi yiyor." - "The cat is eating." (Examples of the use of the nominative for an indefinite object: "Bir çocuk gördüm." - "I saw a child." "Bir kedi gördüm." - "I saw a cat.")
The accusative - used for DEFINITE direct objects - takes the ending "(y)ı/(y)u/(y)i/(y)ü". Exx. "Adamı gördüm." "I saw the man." (nom., "adam") "Çocuğu gördüm." - "I saw the child." "Kediyi gördüm." - "I saw the cat." "Müdürü gördüm." - "I saw the manager." (nom., "müdür")
The genitive - used to show possesion - takes the ending "(n)ın/(n)un/(n)in/(n)ün". Exx. "Adamın evi" - "The man's house" "Çocuğun evi" - "The child's house" "Kedinin evi" - "The cat's house" "Müdürün evi" - "The manager's house"
The dative - used for indirect objects and to show motion towards - takes the ending "(y)a/(y)e". Exx. "Adama verdim" - "I gave it to the man" "Çocuğa verdim" - "I gave it to the child" "Kediye verdim" - "I gave it to the cat" "Müdüre verdim" - "I gave it to the manager"
The locative - used to show place where - takes the ending "da/ta/de/te" (oops, the nouns I was using won't really work with this one!) "adada" - "on the island" (nom., "ada") "yatakta" - "in bed" (nom., "yatak") "evde" - "at home" (nom., "ev") "kafeste" - "in a cage" (nom., "kafes")
The ablative - used to show place from - takes the ending "dan/tan/den/ten". Exx. "adadan kaçtım" - "I escaped from the island" "yataktan çıktım" - "I got out of bed" "evden kaçtım" - "I ran away from home" "kafesten kaçtım" - "I escaped from the cage"