The "standard" prepositions that are taught at school are

• di ('of', 'belonging to'; used in place of the English genitive)
• a ('to')
• da ('from', 'by')
• in ('in', 'on' with abstract nouns)
• con ('with')
• su ('on')
• per ('for', 'in order to')
• tra ('among', 'between')
• fra ('among', 'between')

When prepositions are used together with definite articles, the preposition and the article are sometimes condensed into a single word. For example, "of the student" becomes "dello studente" and not "di lo studente".

More specifically, the following table lists all the possible combinations (except those not in common use today).

	il	lo	la	i	gli	le
di	del	dello	della	dei	degli	delle
a	al	allo	alla	ai	agli	alle
da	dal	dallo	dalla	dai	dagli	dalle
in	nel	nello	nella	nei	negli	nelle
con	col*	collo*	colla*	coi*	cogli*	colle*
su	sul	sullo	sulla	sui	sugli	sulle

Please note that using these combinations is mandatory: you cannot chose to use plain preposition + article instead. Currently, the proposition con represents the only exception, as con il, con lo, con la, con i, con gli and con le are perfectly acceptable forms.

The prepositions di and da may take an apostrophe and become d' before a vowel. Examples where this is the rule, and not simply a matter of personal preference, are

• d'altra parte, lit. "from other side", meaning "on the other hand"
• d'altro canto, lit. "from other place", as above
• d'altri, "of others" (but di altri is acceptable)
• d'oro, "made of gold", "golden"
• d'argento, "made of silver"
• d'oltreoceano, d'oltralpe, etc.

For euphonic reasons, the proposition a usually becomes ad before a vowel, though this is not mandatory. When the vowel following the preposition is another 'a', using ad can probably be considered mandatory. Examples: ad altri (to others), ad essere or a essere (to be), ad oltranza or a oltranza (ad libitum).

Historically, per has been a combinable preposition (with combined forms pel, pello, pella, pei, pegli, pelle), but this usage is never encountered in contemporary prose, even though it is still present in the dialects of Tuscany.