We use *** with singular, countable nouns mentioned for the first time.

• a/an -> "A blue car came round the corner"

• the - > "The blue car came round the corner."

We use ** to talk about jobs.

• the -> His mother's the doctor.

• a/an -> His mother's a doctor.

We do not use a or an with *** nouns.

• uncountable --> Knowledge makes people powerful.

• countable --> Knowledge makes people powerful.

We do not use a or an with plural *** nouns.

• uncountable --> More women go to university in this country than man.

• countable --> More women go to university in this country than man.

Use ** before words which begin with a vowel sound.

• an -> an app; an email.

• a -> a app; a email.

When the letters 'u' and 'e' produce a 'y' sound, use ***.

• an -> an useful tool; an European student; an university.

• a -> a useful tool; a European student; a university.

When 'h' is silent, use ***.

• a -> a hour; a honest man.

• an -> an hour; an honest man.

*** is used with things we have mentioned before or when it's clear who or what we are referring to.

• A

• An

• The

• No article

We use *** when referring to particular things.

• a -> I love music, but I hate a music my sister listens to.

• the -> I love music, but I hate the music my sister listens to.

We use *** with things that are unique.

• a -> a Sun; a moon;

• an -> an Internet.

• the -> the Sun; the moon; the Internet.