A and An: Indefinite Articles

Use before countable nouns:

• A house, a book, a car.

Do not use with noncount (mass) nouns:

• Bread, furniture, money, news, water.

Signifies nouns that are generic in nature:

• A horse has four legs. (All horses have four legs by nature)

Use before singular nouns only, never plural.

Use an before nouns starting with a vowel sound; use a before nouns starting with a consonant sound:

• An apple, a piano.

An is used with words in which the h is silent: an hour, an honor. A may be used when the h is pronounced, as in a horrid example. A is used with u when it sounds like yew, as in a union, and with o as in a one-way street.

With initials, pronunciation determines the article:

An ess, an en, as in an SAT test, an NSCC student.

A b, a t, as in a BBC program, a TB epidemic.

The: Definite Article

Use with nouns that are specific in nature (countable or mass, singular or plural):

• John lives in a white house. (generic)
• President Clinton lives in the White House. (specific)

Use when there is only one of something:

• The President of the United States, the universe, the moon.

Use with superlative forms of adjectives:

• The fastest, the oldest.

Use for a particular item or just one instance:

• The books for my course are expensive, as opposed to Books are expensive.

Use when the noun has just been mentioned:

• I have a pen and a pencil. The pencil is broken.

Use before the names of musical instruments:

• She plays the flute.

Do not use if the destination implies the activity:

• We go to school (meaning to study).
• We go to the school (meaning the place).
• We go to bed (meaning to sleep).

Do not use in front of geographical names, except:

• Bodies of water--the Atlantic
• Mountain ranges--the Andes
• Names of countries which contain the words "union" or "united":
  
  
  • The Soviet Union
  • The United Kingdom
  • But: France, Japan.