I recently received an e-mail from Judith asking if I could explain the difference between essere and stare and how they are used. I got out my faithful Vocabolario della Lingua Italiana Treccani and … oh povera me! (poor me!) Under the entry stare there are 5 columns of information and for essere? well ‘only’ 3! So having digested all that information I’ll attempt to illustrate the main uses of these two verbs, but please note that this is not, by any means, an exhaustive or definitive answer.
As a general rule it can be said that essere means “to be”, and stare means “to stay”, however they assume different meanings in particular constructions and in some idiomatic expressions:
Stare is always used, when followed by bene, male, meglio, or peggio, to talk about somebody’s health and is, therefore, also used in greetings such as: Ciao, come stai? (Hello, how are you?) Sto bene, grazie (I’m fine, thank you). Come sta tuo fratello? (How is your brother?) Sta meglio, grazie (He’s better, thank you).
Stare bene with an indirect pronoun (dative) means “it suits you”: questo vestito ti sta bene (this dress suits you); il colore marrone non mi sta bene (the color brown doesn’t suit me).
E’ bene, e’ male means, on the other hand, “it’s a good thing, it’s a bad thing”: e’ bene non mangiare troppo (it’s a good thing not to eat too much). E’ meglio, e’ peggio mean “it’s better, it’s worse”: secondo me e’ meglio andare in treno (according to me, it’s better to go by train).
Stare per followed by an infinitive means “to be on the point of, to be just about to”: ti stavo per telefonare (I was on the point of calling you).
It’s also important to remember that stare and essere are not interchangeable in the following constructions:
stare followed by the gerundive expresses the present and past continuous: sto leggendo un libro (I’m reading a book); Giovanni e’ arrivato mentre stavo cenando (Giovanni arrived while I was having dinner).
Essere is always used as a verbo ausiliare (auxiliary verb, or helper) in:the passive form: la pizza e’ cotta nel forno (pizza is baked in the oven); l’albero e’ stato tagliato (the tree has been cut down);
combined past tenses of all the reflexive verbs: mi sono lavata le mani (I washed my hands);
combined past tenses of many intransitive verbs: Giovanni e’ andato al cinema (Giovanni went to the cinema).
There are some situations when essere and stare are interchangeable, in particular when talking about a location: la casa e’ in cima alla collina or la casa sta in cima alla collina (the house is on the top of the hill); l’appartamento e’ al quinto piano or l’appartamento sta al quinto piano (the apartment is on the fifth floor). Both verbs are also synonymous with the meaning of restare, rimanere (to stay, to remain): oggi sono in casa or oggi sto in casa (today I’ll be at home); dalle nove a mezzogiorno sono in ufficio or dalle nove a mezzogiorno sto in ufficio (from nine to midday I’ll be in the office). This interchangeability is however mostly a regional preference, i.e. some regions of Italy will use essere in preference to stare in the preceding examples, and vice versa.
I hope I’ve succeeded in shedding a bit of light on this confusing subject but, as I said, this is just a small summary of the hundreds of idiomatic expressions and constructions involving these two verbs.