It is recommended for a Muslim to have a Will written when he is in good health. In what types are ‘Wills’ categorized in Islam?

Question

Wills are of two types: Obligatory Will, in which a person explains what he owes and what is owed to him of rights, such as a debt, loan and items entrusted to his care; or rights that he owed by other people. In this case the will is obligatory to protect his wealth and to absolve him of responsibility. Recommended Will, which is purely voluntary, such as a will in which a man bequeaths one third or less of his wealth to a relative who is not an heir.