Muslims around the world are preparing for the start of Islam's holy month of Ramadan.

Some countries begin observances Monday.  

The timing of the start of the holiday varies in Muslim communities and countries depending on the sighting of the new moon.  

Ramadan, the ninth month of the Islamic calendar, marks the time 1,400 years ago when Muslims believe the words of Islam's holy book, the Koran, were revealed to the Prophet Muhammed.

During Ramadan, Muslims fast from sunrise to sundown - abstaining from eating, drinking, smoking and sexual relations.  The fast is broken at sundown each day with a feast called "iftaar."  

Some information for this report was provided by AFP and Reuters.