Arabic like many languages uses grammatical cases. Arabic only has three cases: nominative, genitive, and accusative.
However, they are for the most part not written. When Arabic is not written fully vowelled the only cases visible are dual nouns, and sound masculine plural nouns, and indefinite accusative case. Because short vowels, and tanween are not pronounced at the end of sentences cases usually go unpronounced at the end of the sentence. However, in fully vowelled text they are still written when they are not pronounced. Most cases can be avoided by pronouncing each word in its pausal form, however most view that pronouncing each word pausally is incorrect, at the very least it is not considered eloquent.
Cases in the singular and in all irregular plurals
Genitive: ِ i
For indefinite nouns
N: ٌ uN
G: ٍ iN
A: ً aN/aa
Cases in the regular masculine plural
N: ـونَ uuna
Cases in the regular feminine plural
N: ـاتُ aatu
G: ـاتِ aati
A: ـاتِ aati
G: ـاتٍ aatiN
A: ـاتٍ aatiN
Cases on Names
Putting case endings on names is something to be avoided, because it is really tricky. Most names never take case endings. In news broadcasts, names of people, and cities are not given case endings if they are composed of only one word.
Most names that do take cases instead of taking "a,i,u" like most normal words instead use "a,a,u" some even take tanween.