`Eid Al-Fitr is just one day on which it is prohibited to fast. As for the second and third days of Shawwal, it is not prohibited to fast on those days. It is permissible to fast it to make up a missed Ramadan fast or as a voluntary fast.

The majority of scholars said that it is not permissible to fast on the Days of Tashriq whether it is an optional fast, making up a missed fast or fasting in fulfillment of a vow. So, the fasts that you observed on the Days of Tashriq to make up for missed Ramadan fasts, are not valid, and you must repeat them.

If ‘Ashura or ‘Arafah coincides with a Friday, you may fast because your intention is to fast ‘Ashura or ‘Arafah, not to fast on a Friday.

The majority of scholars are of the view that sighting the new moon of Ramadan on the first night of the month is a communal obligation, and if all the people fail to do it then they are sinning.

It is haram to break your without a valid excuse and whoever does not fast has abandoned one of the pillars of Islam, and is committing a grave major sin.