An article is a tiny word before the noun that signals its gender: «der» (m), «die» (f), «das» (n), «die» (plural). There are definite articles (der/die/das — something already known) and indefinite (ein/eine — something new). English «the / a» behaves differently — in German the article is part of the word and you learn them together.

Every German noun has one of three articles: der (masculine), die (feminine), or das (neuter). The plural is always die. The article often doesn't match real-world gender — «das Mädchen» (girl) is neuter. Some endings hint at it (-ung / -heit / -keit take «die»), but only one rule is reliable: learn the article with the word — not «Tisch» but «der Tisch».