Quick Guide to Articles

Definition:

Define the specificity of a noun

Types:

Indefinite Articles
Masculine	Nouns starting with a consonant or vowel	Un	Un ragazzo (a boy)
	Nouns starting with s+consonant or z	Uno	Uno studente (a student)
Feminine	Nouns starting with a consonant	Una	Una donna (a woman)
	Nouns starting with a vowel	Un'	Un'automobile (an automobile)

indicate that the noun being referred to is non-specific or general, whereas

Definite Articles
		Singular	Plural
Masculine	Nouns starting with a consonant	Il	I	Il ragazzo → I ragazzi The boy → The boys
	Nouns starting with a vowel	L'	Gli	L'albero → Gli alberi The tree → The trees
	Nouns starting with s+consonant or z	Lo	Gli	Lo studente→ Gli studenti The student → The students
Feminine	Nouns starting with a consonant	La	Le	La donna → Le donne The woman → The women
	Nouns starting with a vowel	L'	Le	L'automobile → Le automobili The automobile → The automobiles

indicate that the noun being referred to is specific or particular

Agreement:

Vary according to the number, gender, and starting letter of the noun it defines

Placement:

Generally after verbs except for mai, già and ancora which are placed between the auxiliary verb and the past participle