Articles are of two types:
1) Indefinite: A or An
2) Definite: The
When we talk about things that are known both to the speaker and the listener, we use the definite article the.
And, when we talk about things that are not known to the speaker and the listener, we use the indefinite article a or an.
For example, I saw a woman sitting under a tree. The woman held her daughter’s hand tightly.
In the first sentence, we use article (a), as it tells about a woman who we don’t know. But in the second sentence, we use article the because the listener is aware of the woman that the speaker wants to refer to.
General usages of A or An :
A is used before the words that start with a consonant sound:
a boy, a horse, a football, a kite
An is used before the words that start with a vowel sound:
an ass, an orange, an umbrella
Point to be noted: We can use A or An only before the singular countable nouns :
a book Not a books
an orange Not an oranges
Confusions to clear: we must use a before the following words:
European, Eulogy, Euphemism, one-eyed man, union, uniform
Though these words start with a vowel (a, e, i, o, u) letter, we must put A before them. Because we should take into account the sound it makes not the letter itself.
In the same way, some words are followed by an, as what matters is the sound, not the letter.
These words are: Hour, heir, Honour
Usages of The: This is called definite article. It tells us things that we already know about.
1)The boy in the field is a doctor (we know which boy)
2)The book you want is not available now (which book? the book you want)
Some exceptions to notice:
1)Normally articles are omitted before the names of people:
Mr. Smith visits us sometimes
But we can put article a, when we talk about a person we don’t know.
A James came to meet you last night.
Here A James implies that he is a stranger to the speaker.
2)Article is used with the uncountable nouns when it is specific.
The kindness Hazrat Mohammad(s) showed to his enemy cannot be forgotten.
Pass me the sugar (maybe the sugar is on the table).
3)generally articles are omitted before the names of meals:
Have lunch on time
But a is used if there is an adjective before the names of meals and they are used when we specify.
I had a good breakfast.
The dinner we had last night was mouth-watering.
4)when people visit the following place such as school, college, church, university for a primary purpose, article is not used:
A good student goes to school regularly.
Going to school is a student’s job
When we go there for different purposes, article is used:
I met him at the college.