Millions of Muslims are observing the start of Ramadan, a festival that includes a month of fasting and prayer.
This is the second Ramadan to fall during the coronavirus pandemic, meaning some communities will be marking it amid Covid restrictions.
Believers taking part will not eat or drink anything during daylight hours.
Fasting is considered to be an act of worship, which enables Muslims to feel closer to God and strengthen their spiritual health and self-discipline.
Here are pictures from around the world showing preparations for Ramadan and the first day of the festival.
Ramadan falls on the ninth month of the Islamic lunar calendar and starts with the sighting of the new moon, also known as the hilal.
The festival is considered one of the holiest Islamic months.
It's also one of the Five Pillars of Islam; the five principles which Muslims believe are compulsory acts ordered by God.
As well as fasting during daylight hours, Ramadan is a time when Muslims are encouraged to give to charity, strengthen their relationship with God, and show kindness and patience.
As Ramadan begins on 13 April, some Muslim communities will find their traditional practises affected by restrictions to stop the spread of coronavirus.
In the UK, the iftar meal to break the fast at sunset is usually shared with family and friends, but because of the lockdown, such meetings will be restricted.
However, while mixing between households was banned during Ramadan in 2020, this year the festival coincides with the easing of some lockdown rules in England.
Up to six people or two households can now gather outdoors and restaurants will be able to serve meals outdoors.
Elsewhere around the world, similar lockdown restrictions and rules are in place, such as wearing face masks whilst worshipping.
In a tweet, the United Arab Emirates (UAE) authorities asked people to "avoid evening gatherings during Ramadan, limit family visits, and avoid distributing and exchanging meals between homes and families".
In Bangladesh, the government announced a strict lockdown for one week, starting on 14 April.
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