This is a complex topic, especially for a person who hasn't been introduced to them before. Cases apply to nouns and anything associated with nouns (pronouns, adjectives, & articles). For simplicity, think of a verb and how it is
conjugated for different contexts (I, you, past, future, etc.). Cases are used to "conjugate" nouns so to speak, depending on how they are used in the sentence (I know, it's icky, but you get used to it just like anything).
But, instead of using the word
conjugate, we say
decline. It is said that a noun
declines in languages like Latin and German (and lots of others). In Latin there are 5 cases and in German there are 4 cases. You will decide which case to use based on how the noun is used in the sentence.
Here are the German cases as mentioned by Francis, and some quick guidelines:
Nominative
Used when the noun is the subject of the sentence
Accusative
Used when the noun is the direct object of the sentence
Dative
Used when the noun is the indirect object of the sentence
Genitive
Used to show possession.
Again, this just a quick overview. There will be some exceptions to the above of course, but you can rely on the above as a foundation for learning these cases.
Quick Examples (subject in bold, direct object in italics):
The man reads the
book.
The woman has a
computer.
Although it's hard to see the cases in English, they do exist (we have subjective cases and objective cases). At the very least we know how to distinguish between the subject and the direct object. So when we translate into German, we must first decide what
function each noun has in the sentence, then choose the appropriate case.
Since
The man and
The woman are the subjects they will be translated using the nominative case. Since
the book and
a computer are direct objects they will be translated using the accusative case.
Der Mann liest
das Buch.
Die Frau hat
einen Computer.
But if you switch around the subject/DOs you can see how they change based on function (just pretend it makes sense :wink:):
Das Buch liest
den Mann (The book reads the man).
Ein Computer hat
die Frau (A computer has the woman).
Notice the change of
der to
den, and
einen to
ein. This is happening because the articles (and nouns, even though it's harder to tell) are responding to the case change.
Here's the definite article (a.k.a the word "the") declined in all its cases (to give you an example of how much more you have to memorize in a language with cases:
Format: masculine / feminine / neuter / plural
Nominative: der / die / das / die
Accusative: den / die / das / die
Dative: dem / der / dem / den
Genitive: des / der / des / der
Some final examples (for the masculine noun
Hund = dog):
Nom: The dog is very pretty: Der Hund ist sehr schön.
Acc: The man has the dog: Der Mann hat
den Hund.
Dat: He speaks to the dog: Er spricht mit
dem Hund.
Gen: That is the dog's bed: Das ist das Bett
des Hunds.
Ok, there's a lot more to it than that, but hopefully that'll help you out in getting the basics down. Cheers!
Oh, and if you manage to make him eat the things on his desk, don't forget to take a picture...very useful for blackmail purposes j/k