Indefinite and Definite Articles

Indefinite Articles—a, an

an—used before singular count nouns beginning with a vowel (a, e, i, o, u) or vowel sound:

• an apple, an elephant, an issue, an orange

a—used before singular count nouns beginning with consonants (other than a, e, i, o, u):

• a stamp, a desk, a TV, a cup, a book

Definite Article—the

Can be used before singular and plural, count and non-count nouns 

1. Indefinite Article (a, an)

Used before singular nouns that are unspecified:

• a pencil
• an orange

Used before number collectives and some numbers:

• a dozen
• a gallon

Used before a singular noun followed by a restrictive modifier:

• a girl who was wearing a yellow hat

Used with nouns to form adverbial phrases of quantity, amount, or degree:

• I felt a bit depressed.

2. Definite Article (the)

Used to indicate a noun that is definite or has been previously specified in the context:

• Please close the door.
• I like the clothes you gave me.

Used to indicate a noun that is unique:

• Praise the Lord!
• The Columbia River is near here.

Used to designate a natural phenomenon:

• The nights get shorter in the summer.
• The wind is blowing so hard.

Used to refer to a time period:

• I was very naïve in the past.
• This song was very popular in the 1980s.

Used to indicate all the members of a family:

• I invited the Bakers for dinner.
• This medicine was invented by the Smiths.