Article a/an

Article a/an

1. a/an -> one

A and an have the meaning of one.
When you use countable nouns, If it is singular nouns, you should use countable
nouns with article (a/an), and if it is plural nouns you should use plural forms of
the nouns.

(ex) I have an apple. (one)
(ex) I have two apples.

2. any, every -> represent something

In this case, a/an have the meaning of every or any.

(ex) An owl can see in the dark.
(ex) A frog eats insects.

3. any one or a certain, unspecific things

You can use a/an when you are thinking of unspecific things.
When you don't know about a person, you can use a/an with the person.

(ex) I have a book about internet.
(ex) A man came to me, and he asked me where a library was.

4. emphasis

You can use a/an after negative, when you need to emphasize something.

(ex) He didn't tell us a thing about his travel.

5. for each or per

A/an have the meaning of for each or per.

(ex) It cost $2 a kilogram.
(ex) I play computer games 4 times a week.

6. difference between 'a' and 'an'

'a' is used in front of consonants.
'an' is used in front of vowels (a,e,i,o,u)

Article 'a'	Article 'an'
a book	an apple
a man	an illness
a pen	an antenna

You must be careful, in case of 'u' and 'h'.
When 'h' is not pronounced, you should use article 'an' and when 'u' is
pronounced like the consonant, you should use article 'a'.

Article 'a'	Article 'an'
a university	an understanding
a use	an unexpected accident
a hospital	an hour
a horse	an honors

(ex) I'll go to your house in an hour.
(ex) He has to choose a university before taking an examination.