Adjectives are used both predicatively and attributively, as in English. A predicate (also called predicative) adjective is one that does not stand in front of a noun, i.e. it is not used attributively like one standing in front of a noun, e.g. ‘His car is red’ (a predicate adjective), but ‘his red car’ (an attributive adjective). Predicate adjectives are invariable, i.e. they do not take endings, thus Sein Auto ist rot. But attributive adjectives must agree in gender, number and case with the noun they precede, thus sein rotes Auto (neuter, singular, nominative). And here lies another bothersome aspect of German which takes some mastering.