Gender: der, die, das

Every German noun has a gender, and its article shows it:

• der — masculine: der Vater, der Bruder, der Arzt
• die — feminine: die Mutter, die Schwester, die Straße
• das — neuter: das Kind, das Baby, das Handy

For people, the article usually matches the person: der Vater, die Mutter. For things there’s no rule you can see — so always learn a noun with its article: not just Handy, but das Handy.

Three helpers:

• In the plural, the article is die for every gender: die Brüder, die Kinder. (That is the basic form you learn with each noun; Unit 8 shows what the cases do to it.)
• Words made small with the ending -chen are always das — even das Mädchen and das Brötchen. It has to be that ending: der Kuchen is not one.
• Compound nouns take the article of their last part: das Telefon + die Nummer → die Telefonnummer.