|articles (gli articoli)
There are two types of articles: definite, or determinate (the equivalent of the English "the") and indefinite or indeterminate (the equivalent of the English "a" or "an").
The forms of the articles always vary according to the gender and number of the noun to which they refer; also, the first letter of the noun affects the form of the article.
articolo determinativo (definite article)
lo: for masculine singular nouns beginning with z or s+consonant
il: for masculine singular nouns beginning with all other consonants
l': for masculine singular nouns beginning with any vowel
la: for feminine singular nouns beginning with any consonant
l': for feminine sigular, beginning with any vowel
articolo indeterminativo (indefinite article; singular only)
una: for feminine nouns beginning with any consonant
un': for feminine nouns beginning with any vowel
uno: for masculine nouns beginning with z or s+consonant
un: for all other masculine nouns
The definite article is used much more in Italian than in English: for example, with abstract and generic nouns (amo la vita=I love life), with seasons and times of day (non mi piace l'inverno=I do not like winter; sono le 4=it is 4 o'clock), with names of countries and regions (la Spagna è vicino all'Italia=Spain is near Italy; la mia regione è il Lazio=my region is Lazio); etc.