Article A, An, The

Articles are a kind of adjective, they show how particular or how general a noun is. There are three kinds of article: the, a/an, and having no article, zero article.

1. A/An – Indefinite Article

A is used for indefinite things. For example:

• "My daughter really wants a car for her birthday." This refers to any cat. We don't know which cat because we haven't found the cat yet.
• "Somebody call a policeman!" This refers to any policeman. We don't need a specific policeman; we need any policeman who is available.
• “I have a book.” I don’t have a specific book, just any book in general.
• “She lives in a house.” Again, the house is just a general house, not a particular house.

An is used for indefinite things. For example:

• "When I was at the zoo, I saw an elephant!" Here, we're talking about a single, non-specific thing, in this case an elephant. There are probably several elephants at the zoo, but there's only one we're talking about here.
•  He is an English teacher.

 Remember, using a or an depends on the sound that begins the next word. So...

• a + singular noun beginning with a consonant: a boy; a car; a bike; a zoo; a dog
• an + singular noun beginning with a   vowel: an elephant; an egg; an apple; an idiot;an orphan
• a + singular noun beginning with a consonant sound: a user (sounds like 'yoo-zer,' i.e. begins with a consonant 'y' sound, so 'a' is used); a university; a unicycle
• an + nouns starting with silent "h": an hour. Sometimes this is optional, for example: a hotel, or “an hotel”. Here the “h” sound in hotel is pronounced.

• a + nouns starting with a pronounced "h": a horse 
• In some cases where "h" is pronounced, such as "historical," you can use an. However, a is more commonly used and preferred. For example: A historical event is worth recording.

Occasionally this is not optional, for example: an honor, not a honor. The “h” sound in honor is not pronounced, so this word actually starts with the vowel sound “o”. As a result, we need to use an.

2. The – Definite Article

A definite article indicates that its noun is a particular one (or ones) identifiable to the listener. It may be something that the speaker has already mentioned, or it may be something uniquely specified. The definite article in English, for both singular and plural nouns, is the.

·         The children know the fastest way home.

The sentence above refers to specific children and a specific way home; it contrasts with the much more general observation that:

·         Children know the fastest way home.

The latter sentence refers to children in general, perhaps all or most of them.

Likewise,

·         Give me the book.

refers to a specific book whose identity is known or obvious to the listener; as such it has a markedly different meaning from

·         Give me a book.

which does not specify what book is to be given.

The definite article can also be used in English to indicate a specific class among other classes:

The cabbage white butterfly lays its eggs on members of the Brassica genus.

3. Zero Article

Zero article is generally for when something is seen as neither definite or indefinite, it simply exists.

Zero article is used in front of plural countable nouns. For example:

·         I like eggs. I like an eggs.

·         Flowers are beautiful. A flowers are beautiful.

Zero article is used in front of singular uncountable nouns. For example:    

·         I like strawberry. I like a strawberry.

·         Music is fun. The music is fun.

Zero article is used in front of proper nouns. For example:

·         My name is Kevin. My name is a Kevin.

·         I live in Seoul. I live in a Seoul.