Indefinite Articles in Italian (un, uno, una, un')

In Italian grammar, *Indefinite Articles (Articoli indeterminativi)* correspond to English 'a / an' and introduce a countable, singular entity not previously identified or specified:

*1. Masculine Forms (un vs. uno): - un: Used before masculine singular words starting with a vowel or most single consonants: un libro (a book), un ragazzo (a boy), un amico (a male friend), un albero (a tree). Note: un before a masculine vowel never takes an apostrophe (un amico, never un'amico)! - uno: Used before masculine singular words starting with s + consonant (s impura), z, gn, ps, pn, or x: uno studente (a student), uno zaino (a backpack), uno psicologo (a psychologist), uno zio* (an uncle).

*2. Feminine Forms (una vs. un'): - una: Used before feminine singular words starting with any consonant: una casa (a house), una ragazza (a girl), una studentessa (a female student). - un' (with elision and mandatory apostrophe): Used strictly before feminine singular words starting with a vowel: un'amica (a female friend), un'idea (an idea), un'ora* (an hour).

Plural Equivalent: Italian indefinite articles have no direct plural forms; instead, the *partitive article (dei, degli, delle) or words like alcuni / alcune are used to express 'some': Ho comprato dei libri* (I bought some books).