Is it obligatory to have prior knowledge of the necessity to formulate the intention to fast Ramadan during the night, and does ignorance of this entail making up the month?

According to the majority of scholars, the intention (niyyah) to fast Ramadan each night is obligatory, because each day is an independent act of worship, contrary to those who say that a single intention for the entire month suffices. The place of intention is the heart. So, if it occurs to a Muslim's heart at night that he will fast the next day, then he has made the intention. Vocalizing it is not a condition. Therefore, the fast of one who intends each night to fast the following day of Ramadan is valid, and no make-up fast is required of him.