Personal Pronouns (Subject) in Italian

Personal pronouns (subject) take the place of a noun and define who does the action.
Italian pronouns are:

In Italian pronouns aren't used as frequently as in English because the conjugation of the verbs usually suggests who's doing the action.

However, they are usually used to highlight the subject's identity:
Siamo andati a Roma ma io volevo andare a Firenze (We went to Rome but I wanted to go to Florence)
In this case the pronoun "io" is used to highlight that "I" wanted to go elsewhere.

They're used to avoid misunderstandings in those cases where conjugation of the verb is the same for more than one subject, e.g. in the present subjunctive:
Penso che tu abbia ragione (I think you're right)
In this case the pronoun tu is used to avoid a misunderstanding with the verb form abbia that might refer to the pronouns I, you, she, he, it.

Nowadays the pronouns "egli", "ella", "esso", "essa", "essi" and "esse" are used only for grammar examples and verb conjugations and for extremely formal texts. To substitute these forms, "lui", "lei" and "loro" are used:
Lui è un insegnante, lei è un medico, loro vivono insieme (He's a teacher, she's a doctor, they live together).

In Italian there's a courtesy pronoun Lei, used in formal situations for both men and women, and it's conjugated to the third person singular feminine or masculine:
Benvenuto nel nostro ristorante, Lei può accomodarsi (Welcome to our restaurant, please have a seat).