DEFINITIVE ARTICLE

Definition: The definite article may be used as a demonstrative pronoun. It is regularly found before the preposition de or the relative pronoun que:

Examples in Spanish:

the green of the leaves and that of the grass
el verde de las hojas, y el de la hierba .

The definite article is also used with an adjective of any number or gender to form a noun.

the old men
los ancianos

:: The definite article agrees in number and gender with its noun.

the child
el niño

the female cats
las gatas

:: Before feminine singular nouns beginning with a stressed a or ha, the definite article el is used instead of la

the water = el agua
the waters = las aguas

The definite article is almost always used in Spanish:

with a general noun representing an entire class of persons or objects.

do you like music?
¿te gusta la música?

with names of languages, except after the prepositions de or en and immediately after the verb hablar

english
el inglés

they speak spanish
hablan español