The partitive

English can say 'I want bread' or 'I want some bread'. Spanish says just quiero pan, and Portuguese, Catalan and Romanian agree: quero pão, vull pa, vreau pâine. French cannot leave the noun bare: je veux du pain. Italian sits in between: voglio del pane and voglio un po' di pane are both everyday Italian. The little word that means 'an unspecified amount of' is the partitive article: de or di plus the definite article.

French: compulsory

A French noun rarely stands bare. For an unspecified amount of something uncountable, use du, de la, de l': du pain, de la musique, de l'eau; for an unspecified number, des: des amis. Two rules trip everyone up. After a negation, du, de la, des and un, une all shrink to de: je n'ai pas de voiture, il n'y a plus d'eau (but not after être: ce n'est pas du vin, c'est du jus). After words of quantity, just de: beaucoup de pain, un peu d'eau, un kilo de pommes, assez de temps. And verbs of liking take the definite article, because they speak of the thing in general: j'aime le pain, never du pain.

Italian: optional

Italian has the same tool — di + article: del, dello, della, dell', dei, degli, delle — but uses it freely rather than by rule. Compro pane, compro del pane and compro un po' di pane are all good Italian; the partitive adds a shade of 'some'. In the plural, dei, degli, delle work as the plural of un, una: ho visto degli amici 'I saw some friends'. After non it usually disappears: non ho pane.

Spanish, Portuguese, Catalan, Romanian: none

Spanish has no partitive. The bare noun does the job: quiero pan, compramos fruta, no hay leche. For 'some' with plurals, use unos, unas or algunos (tengo unos amigos en Roma); with mass nouns, un poco de or algo de. Spanish del is only ever literal 'of the': comí del pan que trajiste — 'I ate some of the bread you brought' — means a specific loaf. Portuguese and Catalan work the same way (uns amigos, uns amics; um pouco de, una mica de), though Catalan keeps the partitive pronoun en, as French keeps en and Italian ne: en vols? 'do you want some?'. Romanian has a dedicated word for 'some': niște — niște pâine, niște prieteni.