An article is a word that combine with a noun to indicate the type of reference being made by the noun. There are only 3 articles in the English Language in two categories; the definite article (the) and the indefinite article (a, an).
Definite article (the)
A definite article (the) is used before singular and plural nouns that refer to a particular member of a group.
The cows are in the field.
Indefinite article (a, an)
An indefinite article(a, an) is used before singular nouns that refer to any member of a group. An is used when the next word begins with a vowel or a silent (unpronounced) h, as in “an animal” or “an hour.”
A cow is an animal.
Partitive article (some, any)
A partitive article indicates an indefinite quantity of a mass noun; there is no partitive article in English, though the words some or any often have that function.
Do have some fun with any of these toys.
A zero article is the absence of an article; for example, in indefinite plural:
Cows and dogs are animals.
for example, in definite proper noun
I am climbing
— as opposed to—
I am climbing the highest mountain
In informal writing, such as notes or appointments , the definite article and some other particles are often omitted, for example, Must pick up clothes from laundrette today.