The document discusses the usage of the articles "a", "an", and "the" in the English language. It explains that "a" and "an" are called indefinite articles and are used before nonspecific nouns, with "a" preceding words beginning with consonants and "an" preceding words beginning with vowels. It also discusses some exceptions to this rule regarding words beginning with "h" or vowel sounds. "The" is called the definite article and is used before specific or previously mentioned nouns as well as titles of works, places, days, single units, and names of religions or nationalities.