Who is required to fast during Ramadan?

Fasting Ramadan is obligatory for the Mukallaf (accountable) Muslim who is able and resident, with a woman being free from impediments such as menstruation and post-childbirth bleeding. A disbeliever is not obligated to fast, and his fasting is not valid. He is not commanded to make up for it if he embraces Islam, but he will be punished for it in the Hereafter. As for the non-Mukallaf, such as a child or an insane person, fasting is not obligatory for them. The incapable, whether due to a temporary excuse like illness and travel, or a permanent one like chronic illness and old age, has specific rulings regarding making up the fast or paying expiation (Fidyah). As for the traveler, he is permitted to break his fast, and it is preferable for him to do what is easier; if fasting harms him, it is haram. Regarding a menstruating woman or one in post-childbirth bleeding, fasting is not obligatory for her, nor is it valid from her, and she is required to make up for it.