How and when do you use the subjunctive?

You use the subjunctive in Italian when you are uncertain about what you are asking or saying, as the subjunctive means (may/might) when used by itself. You also use it when you hope or wish something, as the subjunctive always implies doubt such as the sentence - I hope the weather is nice tomorrow. There are also certain expressions such as 'Sebbene' 'Benche' 'Nonostante' which always take the subjunctive and, similarly, phrases which end in 'that' (che), such as 'I think that' and 'I hope that' always are followed by the subjunctive since it is not certain that what you think/hope is correct.