👉 In Italian, some verbs allow both the auxiliary essere (to be) and the auxiliary avere (to have):

• Verbs that can be followed or not by a direct object;

• Particular motion verbs that require one or the other auxiliary depending on the communicative function;

• Verbs that do not change communicative function based on the choice of auxiliary.

📌 Verbs that can be followed or not by a direct object

In most cases, verbs that form compound tenses with both the auxiliary essere and the auxiliary avere change the auxiliary if they are followed or not by a direct object (on which the action of the verb falls).

The choice of auxiliary depends on the presence or absence of a direct object on which the action of the verb falls:

• auxiliary avere → when a direct object follows the verb;
• auxiliary essere → when a direct object does not follow the verb.

Compare the sentences from the text:

• Ho cambiato casa.
• Abbiamo cresciuto un bravo ragazzo.

In these first two sentences, casa [house] and bravo ragazzo [good boy] are the "direct objects" on which the action of the verb falls (transitive use of the verb). For this reason, the auxiliary avere [to have] is used.

• Negli ultimi anni sono cambiate molto cose nella mia vita;
• Diego è cresciuto velocemente;

In these other two sentences, the verbs are used in an absolute sense, meaning there is no "direct object" present, or they are followed by an adverb (intransitive use of the verb). In compound tenses, the auxiliary essere [to be] is used.

📚 The verbs iniziare and finire

Iniziare and finire take the auxiliary have or be depending on whether a direct object follows them.

Observe the examples:

• Il concerto è iniziato in anticipo. ↔ La festa è finita alle 3 del mattino.
• Ho iniziato un nuovo romanzo. ↔ Ho finito i compiti per le vacanze.

🚨 Attention! Don't be fooled by prepositions.

Observe the examples:

• Ho iniziato a lavorare a un progetto nuovo.
• Ho finito di leggere un libro molto interessante.

The verbs iniziare and synonyms are followed by the preposition "a" + infinitive, while the verbs finire and synonyms are followed by the preposition "di" + infinitive.

📌 Particular motion verbs

Some motion verbs require the auxiliary be or have based on the meaning or function they express. In general:

• auxiliary essere (to be) → when a place of departure or destination is expressed;
• auxiliary avere (to have) → when one wants to express the action represented by the verb mainly.

Verbs of this type include salire, scendere, correre, volare.

📚 The verbs salire and scendere

With the verbs salire up and scendere, the auxiliary essere is predominantly used. However, when there is an explicit "direct object" on which the action falls, which therefore highlights the motion expressed by the verbs, avere is used.

Compare the following sentences:

• A Bologna sono salito sulla Torre degli Asinelli.
• Sono sceso in cantina per prendere un buon vino.

In these first two sentences, the destination places are clearly indicated and the auxiliary is essere.

• Ho salito il sentiero fino alla vetta della montagna.
• Ho sceso le scale di fretta perché ero in ritardo.

In these other two sentences, the action expressed by the verb falls on "direct objects" such as the stairs and the path, and the auxiliary is avere.

🚨 Attention! Don't be fooled by prepositions.

Observe the examples:

• Sono salito sull’aereo.
• Sono sceso dall’autobus.
The bus and the plane are not the direct objects on which the verb's action falls, so the auxiliary is essere.

📚 The verb correre

An interesting case is represented by the motion verb correre.
In this case too, the function of the verb determines the choice of the auxiliary.

Observe the following sentences:

• Sono corso immediatamente da mio cugino perché aveva bisogno di aiuto.
• Ho corso 10 chilometri senza mai fermarmi.

The auxiliary essere indicates "moving towards a destination" (to my cousin), and the auxiliary avere indicates the action of running itself.

📌 Verbs that maintain the same communicative function regardless of the choice of auxiliary

Some verbs maintain the same meaning with both the auxiliary essere and the auxiliary avere. Among these are the verb to live and verbs that indicate meteorological phenomena.

📚 A frequently used verb: vivere

The verb vivere allows both the auxiliary essere and the auxiliary avere.

Observe the sentences from the starting text:

• È vissuto in una casa indipendente.
• Io ho vissuto sempre in centro.

In common usage, the auxiliary avere is predominantly used without making mistakes and without changing the general meaning of the verb.

However, a slight difference in the function of the verb would require using one auxiliary or the other: the auxiliary essere indicates a completed action, thus expressing an event; the auxiliary avere indicates an action in its development.

Examples:
• Mio nonno è vissuto fino a novantadue anni → ended action.
• Ho vissuto a Milano per quindici anni → action still in development.

In some expressions, it's possible to find a "direct object" even after the verb vivere. In this case, the choice of auxiliary is avere.

Examples:
• Ho vissuto un’esperienza unica.
• Valerio ha vissuto un periodo difficile.
• Francesca e Paolo hanno vissuto una storia d’amore bellissima.

📚 Verbs that indicate meteorological phenomena

The most common impersonal verbs that indicate meteorological or atmospheric phenomena are piovere, diluviare, nevicare, gelare, grandinare, tuonare.

Both auxiliaries are allowed with these verbs, although, in current language usage, the form with the auxiliary avere tends to prevail.

These are common sentences:

• Ieri è piovuto tutta la mattina. ↔ Ieri ha piovuto tutta la mattina.
• Oggi è diluviato senza interruzione. ↔ Oggi ha diluviato senza interruzione.
• La settimana scorsa è nevicato. ↔ La settimana scorsa ha nevicato.

In sentences where the duration of the action, i.e., of the meteorological event, is explicitly indicated, the auxiliary avere should always be used.

Example:
• Ieri ha piovuto tutto il giorno.