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Use "a" before words that begin with vowel sounds. Know that "a" is an indefinite article that is used before singular nouns when the referent (the exact thing that you are referring to) is unspecified.
For example, when someone says, "Bring me a banana," the listener knows that the speaker wants a banana (or the idea of a banana) but the speaker has not requested a specific banana. They cannot see the banana. They have not explained where a specific banana is. Therefore, the banana is unspecified.
Use "an" before words that begin with consonant sounds. "An" has the same function as "a"—it is an indefinite article used before singular nouns when the referent is unspecified.
Understanding "a" and "an"
As seen in their definitions, "a" and "an" serve the same grammatical purpose. The key difference between the two words is their pronunciation (UH vs. UHN). Because of their different pronunciations, "a" is used before consonant sounds, while "an" is used before vowel sounds:
A apple (creates a choppy sound)
An apple (creates a smooth connection)
An banana (back-to-back consonants are difficult to pronounce)
A banana (a vowel followed by a consonant sound is easy to pronounce)
The use of these two articles can be seen in the following sentence, which uses both correctly.
When I went out for dinner last night, I had an angus steak, a glass of wine, and a dessert.
Now, there are a couple of key tips and tricks to remember when using "a" vs. "an." In the following sections, we will share these tricks so you can use these articles correctly every time.
When to use "a"
Usually, the indefinite article "a" is used before a word that begins with a consonant. However, this rule does not always hold—what really matters is the sound of the first letter of the word, not the letter itself. So, if a word begins with a vowel but the first sound is a consonant (e.g., union, pronounced YOON-yuhn), then "a" is generally used. Here are a few examples:
John was not impressed with the restaurant, so he gave it a one-star review.
He thought perhaps the food would be better if he moved to a European country.
Although the word "a" is by far most commonly used as an indefinite article, it is worth noting here that there are a few other uses or definitions of the word.
1. "A" can mean "the same." For example:
Birds of a feather flock together.
2. "A" can be used as a function word to form an adverbial phrase of quantity, amount, or degree. For example:
She felt a bit tired.
3. In certain situations, "a" can be used as a preposition meaning "per." For example:
She was racing along at a mile a minute.
Now that you know all about "a," let's take a closer look at its friend "an."
When to use "an"
As mentioned before, "an" normally precedes words that begin with a vowel. However, "an" is also used before words that begin with consonants if the first sound of the word is a vowel. So, for example, although the nouns "x-ray" and "FBI agent" do not begin with a vowel, they do begin with a vowel sound when pronounced aloud; therefore, they would take the article "an" rather than "a." That's why a good trick to remember when you are deciding whether to use "a" or "an" is to read the word aloud. Here are some examples.
Jane made an appetizer for the upcoming Christmas party. (Used before a vowel)
The appetizer took so long to make that she arrived at the party an hour late. (Used before a consonant with a vowel sound)
As with "a," there is an alternative definition for "an" that you may encounter in English writing or speech: a preposition meaning "per."
She drove to the party at sixty miles an hour.
Remembering "a" vs. "an"
In summary, if you are ever unsure about when to use "a" or "an," just remember the simple trick of reading the word out loud, deciding whether it begins with a vowel or consonant sound, and using "a" before words beginning with a consonant sound and "an" before words beginning in a vowel sound.
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