German articles

The n-declension

A group of masculine nouns takes -n in every case except the nominative.

A dictionary prints der Junge, and every sentence after that says den Jungen, dem Jungen, des Jungen. It is a small closed group, it is almost all people, and you can read most of its members off their ending.

der Junge through the cases

One ending, three cases. The plural is die Jungen.

Nominativ	der Junge
Akkusativ	den Jungen
Dativ	dem Jungen
Genitiv	des Jungen

Which nouns belong here

-e: Masculine nouns ending in -e — almost all of them people or animals.
der Junge
der Kunde
der Kollege
der Löwe
der Hase
-ent, -ant, -ist, -at, -oge, -graf, -nom, -soph: The borrowed endings for people, the same ones that make a noun der.
der Student
der Praktikant
der Polizist
der Soldat
der Biologe
-e: Nationalities built with -e. The feminine forms (die Türkin, die Chinesin) decline normally.
der Franzose
der Chinese
der Brite
der Türke
der Grieche
—: A short list of irregulars — and the ones you meet earliest.
der Herr
der Mensch
der Nachbar
der Bauer
der Held
der Bär

The six that add -(e)ns

These go like the group above, except that the genitive takes -ns — das Herz takes -ens, and it is the only neuter in German that does this at all.

der Name → des Namens
der Gedanke → des Gedankens
der Wille → des Willens
der Glaube → des Glaubens
der Buchstabe → des Buchstabens
das Herz → des Herzens

Why it is worth the trouble

Every noun on this page is a person you will end up talking about: it is “Ich frage den Studenten”, never “den Student”.