Das ist eine Tasche.
The indefinite article is used …
- when we are talking about the type of object or person being referred to in general.
- when the object or person is not yet known and has not been mentioned before.
Das ist die Tasche von Jenny.
The definite article is used …
- when talking about a particular object or person that is already known to the speaker or listener.
- when further information is known about a person or an object, e.g. to whom it belongs.
Grammatical terms in German:
der bestimmte Artikel: The articles der, die, das are definite articles.der unbestimmte Artikel: The articles ein, eine are indefinite articles.