The correct use of articles, ‘a’, ‘an’ or ‘the’, is one of the most difficult things to learn in the English language. Few native English speakers would be able to explain why they chose to put ‘a’, ‘an’ or ‘the’ in front of some words but not others, and there are even variations among those who do know.
If you are a total beginner a safe rule would be - if in doubt put them in - you are more likely to be right than wrong!
Here are a few of the more basic rules - for a more comprehensive overview see Swan Practical English Usage.
- Articles are NOT normally used with uncountable nouns or plurals. E.g. I feel full of energy. Holidays are fun. They are almost always used with singular countable nouns. E.g. A book is a good way to pass the time on a rainy day.
- Articles are used when we are writing about particular things, but are not usually used for things in general. E.g. The water was cold. We are talking about a particular swim or drink perhaps. Water is essential for living things. Now we are talking about water in general.
- ‘The’ is a definite article. It is used when we expect someone to know who or what we are talking about. E.g. "The boy over the road has a skateboard." We know who the boy is, and which road we are talking about, but there is nothing special about the skateboard. If we said "The boy over the road has the skateboard." the meaning has now changed. Now we also know something significant about the skateboard - maybe it is one that was lost, or it is one that the listener also knows about.
- ‘A’ or ‘an’ can only be used with singular nouns. ‘An’ is used in front of words which start with a vowel - ‘a, e, i, o, u’. E.g. An apple fell off a tree. ‘An’ is also used in front of acronyms or words which sound as if they start with a vowel. e.g. An FSA is a finite state automaton.
There are many more details and exceptions to the use of articles that the more advanced speaker should get to know - Swan has approximately 14 pages on the use of articles - it is an excellent reference book for NESB students.
