Fasting Ramadan is obligatory on every responsible and fit Muslim. But there are other times when it is recommended to make voluntary fasting, after the traditions of Prophet Muhammad. Among these times are Mondays and Thursdays of every week, a few days of each month in the two months heralding the coming of Ramadan, i.e., Rajab and Sha'ban, six days after Ramadan following the 'Eid-ul-Fitr Day. Besides, it is always compensating to fast any day of any month of the year, except the 'Eid Days and Fridays when no Muslim should fast.

However, we may repeat that the only obligatory fasting is that of Ramadan - which may be 29 or 30 days, depending on the moon's positions. This is a pillar of Islam, and any failure to observe it without reasonable excuses is a grave sin in the sight of God.

Who Must Fast?
Fasting Ramadan is compulsory upon every Muslim, male or female, who has these qualifications:

To be mentally and physically fit, which means to be sane and able.

To be of full age, the age of puberty and discretion, which is normally about 14. Children under this age should be encouraged to start this good practice on easy levels, so when they reach the age of puberty they will be mentally and physically prepared to observe fasting.

To be present at one's permanent settlement, your home town, one's farm, and one's business premises, etc. This means not to be on a journey of about fifty miles or more.

To be fairly certain that fasting is unlikely to cause you any harm, physical or mental, other than the normal reactions to hunger, thirst, etc.

Exemption From Fasting:
These said qualifications exclude the following categories:
Children under the age of puberty and discretion.

Insane people who are unaccountable for their deeds. People of these two categories are exempted from the duty of fist, and no compensation or any other substitute is enjoined on them.

Men and women who are too old and feeble to undertake the obligation of fast and bear its hardships. Such people are exempted from this duty, but they must offer, at least, one needy poor Muslim an average full meal or its value per person per day.

Sick people whose health is likely to be severely affected by the observance of fast. They may postpone the fast, as long as they are sick, to a later date and make up for it, a day for a day.

Travelers may break the fast temporarily during their travel only and make up for it in later days, a day for a day
Pregnant women and women breast-feeding their children may also break the fast, if its observance is likely to endanger their own health or that of their infants. But they must make up for the fast at a delayed time, a day for a day.

Women in the -period of menstruation (of a maximum of ten days or of confinement (of a maximum of 40 days).; They must postpone the fast till recovery and then make up for it, a day for a day.

It should be understood that here, like in all other Islamic undertakings, the intention must be made clear that this action is undertaken in obedience to God, in response to His command and out of love of Him.

The fast of any day of Ramadan becomes void by intentional eating or drinking or smoking or indulgence in any intimate intercourse, and by allowing anything to enter through the mouth into the interior parts of the body. And if this is done deliberately without any lawful reason, this is a major sin which only renewed repentance can expiate.

If anyone, through forgetfulness, does something that would ordinarily break the fast, on observance is not nullified, and his fast stands valid, provided he stops doing that thing the moment he realises what he is doing.