Der
Der is a key word in German grammar serving as a definite article and, in some cases, as a relative pronoun. As a definite article, der marks masculine singular nouns in the nominative case, for example Der Mann schläft (The man sleeps). It is one of the three definite articles in German, alongside die (feminine and plural) and das (neuter).
Der changes form only in the sense of its case for masculine singular nouns: nominative der, genitive
Beyond its role as a determiner, der also serves as a relative pronoun for masculine singular antecedents,
Der appears in proper nouns and titles, such as Der Spiegel or Der Tagesspiegel, where it is
The form der derives from the definite article lineage in West Germanic languages and is cognate with