S + V+ a+ sing noun (with consonant)

Definite and indefinite articles

Use:
1) Use a before a singular noun. S + V+ a+ sing.noun (with consonant)

I've got a brother and a sister.
Use an if the noun begins with a vowel. S+V+ an + Sing.noun (with vowel)
I've got an aunt in Texas.

2) Use plural nouns or uncountable nouns to talk about things in general. Don't use an article here.

I like cats.

Dolphins are very intelligent.
Crime is increasing.
3) Use the to talk about one particular thing, or a particular group of things.
Books are interesting. The book on the table is interesting.
Children are noisy. The children in this class are noisy.

4) Use a to introduce a new thing or person. Use the when you already know this person or thing.

There is a restaurant near my house. The restaurant serves good food.

5) Use the when there is only one of these things. The + S + V+

The moon is very big tonight.
My dad is the only doctor in our village.
Joe is the best student in the class.

6) Use the when there are many things, but it is clear which one you mean.

Let's go to the pub! We need to go to the supermarket.

7) Most 'general' nouns do not use an article.

Life is not the same as it used to be NOT: The life…

Health is important to everyone. NOT: The health…

We're worried about pollution. NOT: The pollution…

But some general nouns use the:

the environment : People are increasingly worried about the environment.
the weather: What's the weather like today?
the countryside :I love walking in the countryside.
the sea / ocean I'd love to live near the sea.
the radio There's an interesting programme on the radio.
the theatre / cinema We went to the theatre last night.
the economy The economy is affecting everyone.
Common mistakes:
1) Some students use the when they talk about things in general.
I love the romantic films! => I love romantic films!

2) Some students use singular nouns without a or the.

I want book about the weather. => I want a book about the weather.
3) Some students use the when they talk about things in general.
I want the book about the weather. => I want a book about the weather.