There are two types of articles basically in English namely: Definite articles (the) and indefinite articles ( a, an, some).Definite articles are determinants used to identify a specific or a particular thing.
The boy – This mean a specific boy not just any boy.
The girl – This means a specific girl not just any girl.
‘The’ is invariable, so can be used for both genders (Though gender difference that occurs in R omance languages like French, Spanish etc., is not as important in English as in those language.)
Indefinite articles are determinants used to generalize an item.
I gave a boy in the class – This could be any boy in the class.
We saw an office in town – This could be any office in the town.
I gave some girls in the class – This refers to more than one girl.
A is used before words starting with a consonant sound.
AN is used before words starting with a vowel sound.
SOME is used as plural of both a and an.
E.g. a boy, a pig, a cup but an office, an umbrella, an egg.