> What does "backed by the full faith and credit of a stable entity" even mean? Why does it matter? I understand it to meant that the country in question will

> What does "backed by the full faith and credit of a stable entity" even mean? Why does it matter? I understand it to meant that the country in question will be a currency-recipient of last resort: the country will always accept taxes paid in this currency, and will use this currency to charge for government services and pay its employees. This ensures that there's always a market for the currency -- something that you don't have a guarantee of otherwise, unless the mode of payment has non-financial uses (like rice, cloth, nails, or cows).