Muslims throughout the world are celebrating Ramadan, amonth of fasting and great blessings, of charity and spiritual joy for all, which began Tuesday evening and will continue until Sept. 15 when the festival "Idul-Fitr Day" marks the end of fasting.

During Ramadan, the month the Qur'an was sent to mankind for his guidance, adult Muslims abstain from all food, drink and sexual activities from shortly before dawn till sunset every day. These restrictions are lifted at night.

Rules of fasting may be ignored by the sick, those who travel distances exceeding 50 miles and women who are pregnant or breast-feeding. Days of fasting, which are missed for these reasons must be made up after Ramadan when the cause of the exemption is over.

Those exempted from fasting permanently because of old age or incurable disease, must substitute each day they cannot fast with the feeding of a poor person for one day, or pay the cost of food, estimated at $3 a person by the Islamic Center, to feed a poor person.

The whole month is regarded as a Muslim holiday. Muslims, who are always urged to be charitable, are urged to be even more so during Ramadan, and special obligatory charity is due to the poor during the month of Ramadan, to be paid at the end of the month on "Idual-Fitr Day."

Special Ramadan prayers will be said each night at the Washington Mosque.

The festival marking the end of fasting, "Idul-Fitr" on sept. 15, is the grandest festival observed by Muslims, with a special Id prayer being held at 10 a.m.

The next most important annual festival, "Festival of Sacrifice" on Nov. 21, marks the successful conclusion of the pilgrimage season to Mecca.