The chapter's title is 'Articles: a, an, the' and the introduction refers to 'definite and indefinite articles'. 'a' and 'an' are for first mentions or unspecified items, making them indefinite.
Class 6 › English Grammar and Composition › Chapter 3: Articles: a, an, the › Topic: Introduction to articles: a, an, the
Aligned to the NCTB national curriculum.