A or an can precede only singular count nouns; they mean one.
They can be used in a general statement or to introduce a subject which has not been previously mentioned.
Example :
A baseball is round. (general – means all baseball)
I saw a boy in the street. (we don’t know which boy)
An is used before a words that begin with a vowel sound. A is used before words that begin with a consonant sound.
Example :
A book An apple
Some words can be confusing because the spelling does not indicate the pronounciation.
A house (begin with a consonant sound)
An hour (begin with a vowel sound)
A university (begin with a consonant sound)
An umbrella (begin with a vowel sound)
The following words begin with a consonant sound and thus must always be preceded by a.
European
House
Uniform
Eulogy
Home
University
Euphemism
Heavy
Universal
Eucalyptus
Half
Union
The following words begin with a vowel sound and thus must always be preceded be an.
Hour
Uncle
Heir
Umbrella
Herbal
Unnatural
Honor
Understanding
The initial sound of the word that immediately follows the indefinite article will determine whether it sound be a or an.
Example : An umbrella a white umbrella
An hour a whole hour
THE
The is used to indicate something that we already know about or something that is common knowledge.
Example :
The boy in the corner is my friend. (that speaker and the listener know which boy)
The earth is round. (there is only one earth)
With non-count nouns, one uses the article the if speaking in specific terms, but uses no article if speaking in general.
Example :
Sugar is sweet. (general – all sugar)
The sugar on the table is from cuba. (specific – the sugar that is on the table)
Normally, plural count nouns, when they mean everything within a certain class, are not preceded by the.
Normally a proper noun is not preceded by an article unless there are several people or things with the same name and the speaker is specifying one of them.
Normally words such as as breakfast, lunch, dinner, school, church, home, collage, and work do not use any article unless to restrict the meaning.
USE THE WITH
DON’T USE THE WITH
Oceans, rivers, seas, gulfs, plural
Lakes
The Red Sea, the Atlantic
Ocean, the Persian Gulf
The Great Lake
Mountains
The Rocky Mountains
The Andes
Eart, Moon
The Earth, The Moon
Singular lakes
Lake Geneva
Lake Eric
Mounts
Mount Vesuvius
Mount McKinley
Planets, Constellations
Venus, Mars, Earth, Orion
