A or An are used before nouns to talk about something the listener or reader does not know about.
I have a problem. Do you know what it is?
• I was born in a town.
(The reader doesn’t know which town and no vowel sound so, a)
• They are a company which sells chocolate.
(lots of companies sell chocolate so the listener doesn’t know which company is being talked about and no vowel sound so, a)
• I want to buy an umbrella.
(There are lots of umbrellas to buy, but we don’t know which one. Here there is a vowel sound so we use an)
A before nouns
A should be used before countable nouns that talk about one person or thing. (3:15)
A or An before nouns?
An should be used before nouns that talk about one person or thing, and begin with a vowel sound (a, e, i, o, u). (3:15)
Vocabulary Video Lesson: Censorship
This vocabulary lesson will help you define censorship, black out, blur out, grawlix, illicit, restriction, suppression, expletive and bowdlerize. (8:00)