1. Articles are words that are used before nouns to indicate whether the noun is specific or general.

1. In English, there are two articles: "a" and "an."

1. "A" is used before singular nouns that begin with consonant sounds. Examples include "a book," "a car," and "a house."

1. "An" is used before singular nouns that begin with vowel sounds. Examples include "an apple," "an elephant," and "an umbrella."

1. The indefinite article "a" is used to introduce a noun that is not specifically known to the reader or listener. Examples include "I saw a dog in the park" and "I'm reading a book."

1. The indefinite article "an" is used in the same way as "a," but it is used before nouns that begin with a vowel sound. Examples include "I saw an elephant at the zoo" and "She's writing an essay."

1. There is also a definite article in English, which is "the."

"The" is used before singular and plural nouns, as well as before uncountable nouns, when the noun is specific or already known to the reader or listener.  

1. "The" is also used before superlatives and ordinal numbers. Examples include "the best," "the first," and "the second."

"The" is not used before plural nouns that begin with a vowel sound when the noun is modified by an adjective. 

There are also no articles used before proper nouns, which are the specific names of people, places, and things. 

It's important to note that the use of articles in English can be quite complex, and there are many exceptions to the rules outlined above.