A special type of adjective is called an article adjective.
There are three articles: "a", "an" and "the". (However,
since "an" is just another form of "a", technically
speaking, there are only two unique articles).
These adjectives are used in front of most nouns to specify
the noun. You wouldn't say "Boy walked quickly"! Instead, you would
say either "The boy walked quickly," or "A boy walked quickly."
In the above sentences, "the" and "a"
are the articles. They tell the reader that a specific boy walked quickly.
The vs. A/An
The two articles “the” and “a” are not interchangeable. They
each have specific situations where they must be used.
Use “the” when you want to specify one specific noun out of
all the same nouns. For example:
The girl jumped out the
low window onto the rosebush.
Here, the three “the’s” specify one particular girl, one
particular window, and one particular rosebush out of all the girls, windows
and rosebushes.
“The” is called a definite article because the subject it is
referring to is a definite (specific) noun out of all the same nouns.
Use “a” when you are not specifying a particular noun.
Consider the following sentence:
A cat is stuck up in a
tree.
In this sentence, we are not talking about any particular
cat or any particular tree. We are just talking about some cat stuck up in some
tree. The article “a” (or an) is used with nouns that are not specific.
“A/an” is called an indefinite article because the subject
it is referring to is an indefinite (not specific) noun.
A vs. An
The articles “a” and “an” are actually two forms of the same
article. However, we have two different forms of this article because each form
is used in a different situation. The rules for using the correct form of the
article are as follows:
Use “a” when the first sound heard after the article is a
consonant. For example:
a car, a beetle, a dinosaur, a pair
of scissors, a zebra.
Use “an” when the first sound heard after the article is a
vowel. For example:
an alpine butterfly, an eatery, an
igloo, an octopus, an umbrella.
Sometimes, even though the word following the article may
start with a consonant, you may need to use the article “an” if the first sound
heard is that of a vowel. Similarly, sometimes you may have to use the article
“a” before a word that starts with a vowel if the first sound heard is that of
a consonant. For example:
It is an honor to meet you.
I don’t think I will ever see a
unicorn.
In the first example, the article “an” is used because in
the word "honor", the “h” is silent, so the “o”, a vowel, is the
first sound heard.
In the second example, the article "a" is used
because the “u” in “unicorn” has the sound of the consonant “y” as in “yell”.
Remember that this rule is based off of the first sound
heard after the article, not the first sound of the noun. In other
words, if there is another word between the article and the noun, then the
article will be based on the first sound of the word in between, not the noun. For
example:
a lazy alligator, a nice eatery, a
very cold igloo, a giant octopus, a heavy umbrella.
Even though the first sounds of the nouns in the above
examples are those of vowels, the first sounds after the articles are those of
consonants, so here the article “a” is used and not "an".
Here are some examples of the opposite:
an artistic person, an enthusiastic
teacher, an impatient boy, an occupied doctor, an underfed pet.
Even though the first sounds of the nouns in the above
examples are those of consonants, the first sounds after the articles are those
of vowels, so here the article “an” is used and not "a".