There are some rules that apply to the use of the definite article in German

1. In German, we have to use the definite article with a person or object that is already known to the speaker.
   Example:
   Die Frau geht mit dem Kind in die Stadt. - The woman takes the child downtown.
2. The definite article refers to a subject that is unique and only exists once.
   Example:
   Die Donau fließt durch Deutschland. - The Danube flows through Germany.
3. In German, we also use the definite article, when naming the date – with this concept German differs from English.
   Please take a closer look at the example.
   Example:
   Heute ist der 20. August. - Today is the 20th of August.
4. German uses the definite article together with the superlative.
   Example:
   Das älteste Mitglied heißt Johannes. - The eldest member is named Johannes.

Let’s move on to the indefinite article.