A noun's case tells how it should be understood in a sentence. In spoken Latin, the case is the way the noun is inflected, but in written Latin, it determines the endings of nouns.

In English, we know how to understand words in a sentence based on their order, but in Latin, word order doesn't (usually) matter!

Let me show you what I mean. In Latin, all of the following sentences mean "The girl loves the boy."

• Puella puerum amat.
• Puella amat puerum.
• Puerum amat puella.
• Puerum puella amat.
• Amat puerum puella.
• Amat puella puerum.

We know how each word is to be understood in the sentence because of the word's case, which we can identify based on the word's ending. The endings for each case are different based on a word's declension and number. You will need to memorize the endings for all 7 cases, singular and plural, of each declension. Sadly, memorizing is a part of Latin. Just repeat the endings over and over out loud until you remember them. Or, practice declining nouns.

Latin has seven cases. Five of them - nominative, genitive, dative, accusative, and ablative - are used a lot, while the other two, vocative and locative, aren't used very much.

Some Latin students use the acronym SPIDA to remember the most common uses of the 5 main cases.
S - subject
P - possession
I - indirect object
D - direct object
A - a lot of meanings

One important thing to remember - nouns in apposition to each other (meaning they name each other) will always be in the same case.

• Ex: Roma urbs magna fuit. --> Rome, the city, was great.

The nouns that are in apposition to each other are in red.
​You see? Urbs (city) and Roma (Rome) name each other, so they are both in the same case - nominative.

Learn more about the different cases and their uses by going to their individual pages. Learn the endings of each case for each declension by going to the pages of the declensions.