This document discusses the three types of articles in English: indefinite articles, definite articles, and zero articles. The indefinite articles are 'a' and 'an', which refer to unspecific nouns. The definite article is 'the', which refers to specific nouns. 'A' is used before consonant sounds, and 'an' is used before vowel sounds. The definite article 'the' indicates a particular noun. Zero articles are used with uncountable plural nouns.