Guide: What is Ramadan?
During the month of Ramadan Muslims fast from dawn until sunset - that means eating nothing while it is daylight.
Children, pregnant women, the sick, the elderly and travellers don't have to fast.
The Qur'an, the holy book followed by Muslims, was first revealed during the month of Ramadan.
This summer Muslims in the UK are facing the "longest" Ramadan in 33 years, as the holy month coincides with the summer solstice, meaning long days of fasting.
At this time of year daylight can last about 16 to 19 hours, depending on your UK location.
The month of Ramadan is a time for spiritual reflection, prayer, doing good deeds and spending time with family and friends.
At the end of the fast, special meals are served and families and friends get together to break the fast. Many Muslims also go to the mosque to pray.
Ramadan is the ninth month of the Islamic calendar. Because Islam uses the lunar calendar (based on the cycles of the moon), the month of Ramadan comes around 11 days earlier each year, so it isn't a fixed date in the Western/solar calendar.
The festival to celebrate the end of Ramadan, and fasting, is called Eid al-Fitr.
Often children are given presents and new clothes.