There's a vacancy for a general node on Italian, which I might get to later if no-one beats me to it. For now I want to restrict myself to pronunciation.
The following is a description of standard Italian (which is traditionally the dialect of Dante's Tuscany, not of Rome). Regional dialects may differ: I don't know much about them.
Vowels
Italian has seven
vowels. Two of them occur only in
stressed syllables; the other five may occur anywhere. The vowels
a i u are as in
father, machine, rule.
The letter e is normally the "ay" sound (but pure, not a diphthong) of French été. But in a stressed syllable it may have the "air" sound of mère. Two words can contrast in which they have: so vénti means 'twenty', vènti means 'winds'; pésca means 'fish', pèsca means 'peach'. But the difference is not shown in writing: so these words are actually written venti, pesca regardless of which vowel they have.
Similarly there are two o sounds, one "oh" (French au), used in unstressed syllables and some stressed syllables, and a lower "aw" sound used when stressed. Again the standard spelling does not distinguish these. (Dictionaries also don't show them, because they vary by region.)
Stress is usually on the second-last syllable: esPRESSo, miLANo (= Milan), mussoLIni. Sometimes it is on the third-last, which is not specially marked in writing: NApoli (= Naples), veNEZia (= Venice). When it's on the final syllable it's marked with a grave accent1: virtù, omertà.
Vowels do not change quality depending on stress the way English ones do (baNAna): in Italian all three have the same "ah" quality. But stress affects length and pitch. In an open syllable (one not ending in a consonant), the stressed vowel is long: so NApoli, ROma, toRIno (= Turin) are pronounced NAApoli, RO-Oma, toRIIno.
Moreover, in the usual comic imitation of an Italian accent, the pitch rises on the stress: giuSEPpe. But in fact the pitch drops on the stress: giuSEPpe.
Consonants
The letters J, W, X, and Y are not used in Italian
2.
b, d, f, l, m, n, p, t, v as in English.
c has two pronunciations, K as in cat, cot, cut before A, O, U; and CH as in cello, chip before I and E: cività 'city' = chee-vee-TAH.
To get the K sound before I or E they write ch: so chi 'who?' is pronounced KEE.
To get the CH sound before A, O, U they write ci: the i here is not a vowel. So ciabatta (a kind of bread) is chah-BAHT-ta, not chee-ah-BAHT-tah.
g likewise has two pronounciations, GH as in gat, got, gut before A, O, U; and J as in gentle, gin before I and E.
The same conventions as with C reverse the sounds: so ghirlando has the same sound as its meaning 'garland'.
And gia, gio, giu are monosyllables JA, JO, JU. So Giovanni is jo-VAHN-nee, not jee-o-VAHN-nee.
gn is NY as in onion, cañon. gl is usually LY as in million.3
h is silent. (It's also used in the combinations CH, GH above.)
qu is always KW as in English, never K as in French or Spanish.
r is strongly rolled in all positions.
s is usually as in sister. Sometimes between vowels it is a Z sound as in Rosa. No one easy rule can be given for this. It is also a Z before voiced letters such as B, D, G: so sbaglio 'mistake' is ZBAH-lyo.
sci, sce have the SH sound of sheep, shape. Before A, O, U this SH sound is written sci, but the i is not a vowel: so sciagura 'misfortune' is shah-GOO-rah. And sch is used for SK: schiavo 'slave' is SKYAH-vo.
z is usually TS as in pizza. Sometimes it's DZ, as in mezzo 'middle'. There is no simple rule for deciding when.
Double consonants
These are always pronounced
double, held long like the N-N in
pen-knife:
anno 'year' is AHN-no.
In a stressed syllable, when a liquid such as m n l r is followed by a different consonant, the liquid is doubled in speech though not in writing: so molto 'much' is MOHL-L-to; venti 'twenty' is VAYN-N-tee.
When a stressed vowel in one syllable meets the opening consonant of the next word, the consonant is doubled in speech. If they're joined together as a single word, it's doubled in writing too. So a 'to' + rivederci 'see you again' is pronounced (and in this case written) with strengthened R: arrivederci.4
Minor phonetic points
t d n l are
dental as in French and Spanish, not
alveolar as in English.
p t c are unaspirated.
1. A recent convention in printing is to use the acute accent for final í and ú and for the higher of the two é ó sounds. I believe this innovation is due to the Einaudi publishing house. I don't know how widespread it is.
2. Of course it uses these in foreign or international words borrowed unchanged. Also, j was formerly used as a consonant where i is now used, as in ajuto, aiuto 'help'.
3. Exception: it's G-L in negligenza.
4. Exception: di 'of' isn't followed by doubling.