Most Muslims globally have started observing this year's Holy Month of Ramadhan.
Ramadhan is a holy month of introspection and prayer for people who profess the Islamic faith.
During this period, Muslims are encouraged to study the Quran and fast.
According to religious literature, prior to becoming a messenger of God, Prophet Muhammad used to retreat to the top cave of Mountain Hira, where he would meditate in solitude "away from the polytheistic culture of tribal Mecca".
Ramadhan is observed in the month that most Muslims believe the Holy Book, Quran, began to be revealed to Prophet Muhammad.
Religious literature say that Muhammad, the founder of the Islam faith, again went to the top of Mount Hira to meditate.
The Prophet, who was 40 years old, is said to have experienced an angelic form appearing before him, commanding him to read, before the first five verses of the Holy Quran were revealed to him.
These incidents marked the beginning of Islam, the revelation of the Quran and the prophetic mission of Prophet Muhammad.
The month of Ramadhan was declared "holy" when Muslims migrated to Medina to escape persecution. It marks the start of the mission of the Prophet and the revelation of the Quran.
During the Ramadhan period, Muslims are obligated to fast every day, from dawn to sunset. Fasting, which is one of the five pillars of Islam, requires abstinence from food and drink.
During fast, Muslims are also discouraged from engaging in sexual contact.
One is, however, free to engage in any of these activities after breaking Iftar, the evening meal with which Muslims end their daily Ramadhan fast.
Breaking the fast is done at the time of the call to prayer for the evening prayer.
Children, pregnant or nursing mothers, women and girls who are in their menstruation are excluded from fasting during Ramadhan.
On later dates, however, they're encouraged to make up for the days they failed to observe the fast.
The end of Ramadhan is marked by a three-day celebration of Eid.
