One gropus is indefinite articles (ein, eine, ...) and in the same group you have possessive articles, negative articles or no articles, and then you have group 2, the definite articles (der, die, das, ...) and in the same group are demonstrative articles (dieser, diese, dieses, ...). Adjective declension can change when using an article from one group as opposed to the other group.
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What are article groups?
One gropus is indefinite articles (ein, eine, ...) and in the same group you have possessive articles, negative articles or no articles, and then you have group 2, the definite articles (der, die, das, ...) and in the same group are demonstrative articles (dieser, diese, dieses, ...). Adjective declension can change when using an article from one group as opposed to the other group.
@@germanwithesther Danke schön