How do you form conditional sentences (periodo ipotetico) in Italian?

In Italian there are 3 different types of conditional clauses, called 'periodo ipotetico'. The 1st type express a real condition, a fact, something about which we are sure of the consequences. It is formed by using present or future indicative in both the protasis (if clause) and the apodosis (principal clause). If the present indicative is used in the protasis, in the apodosis it is possible to use both present or future, as well as the imperative. The 2nd type expresses possibility in the present. It is formed using the imperfect subjunctive in the protasis and the present conditional in the apodosis: Se lui mangiasse meno, sarebbe meglio (if he ate less, it would be better). The third type expresses impossibility, an unreal situation in the past. It is formed by using pluperfect subjunctive in the protasis and past conditional in the apodosis.