The world's 1.5 billion Muslims began observing the holy fasting month of Ramadan on Saturday, blighted by conflict and bloodshed in countries ranging from Afghanistan to Libya.
Ramadan is one of the five pillars of Islam during which Muslims are supposed to devote themselves to praying, giving to charity and fasting from dawn to dusk.
It is sacred because tradition says the Koran was revealed to the Prophet Mohammed during that month.
Although for many Ramadan is a time for families to gather and break the fast with an iftar meal at sunset and socialise, this year it has been marked by violence.
In Afghanistan's eastern city of Khost, a Taliban car bomber killed 13 people in the first major attack at the start of the holy month targeting a CIA-funded militia group.
In the Philippines, security forces intensified a bombing campaign in one of the country's largest Muslim-majority cities where they have been battling Islamic militants.
The Islamic State group, which has been responsible for countless bloody attacks around the world, claimed responsibility for shooting dead 29 Christians on a bus in central Egypt.
Friday's assault on the most populous Arab state's Coptic Christian minority community prompted retaliatory air strikes on jihadists in neighbouring Libya and an outpouring of condemnation.
"With a broken heart and tears in my eyes but after all I wish all my friends a great Happy Ramadan and may God accept all your prayers and fasting for the good of our beloved Egypt," Nabil Hakim, an Egyptian Copt who lives in the United States, posted on Facebook.
Libya has been gripped by chaos since the overthrow and killing of longtime dictator Moamer Kadhafi in 2011, with rival governments and militias vying for power and jihadists taking advantage of the mayhem.
On Friday, forces loyal to the UN-backed unity government battled rival militias in the capital Tripoli.
The health ministry gave a provisional toll of 28 dead and more than 100 wounded, while loyalist forces said 52 of their fighters had been killed in the battles that rocked residential areas.
"This is their gift to the people for the month of Ramadan," a Government of National Accord statement said.
Residents of west Mosul in northern Iraq also did not expect a peaceful Ramadan, far from it as Iraqi forces pressed a broad assault on areas still held by IS jihadists.
Earlier this week, the military said it had dropped "hundreds of thousands of leaflets" on IS-held areas of Mosul, urging "citizens to exit via safe corridors towards security forces".
Ramadan is a month generally marked by piety and sacrifice, and during which Muslims abstain from eating, drinking, smoking and having sex from dawn to dusk.
Civilians in impoverished Yemen, where Iran-backed Shiite Huthi rebels are battling government forces supported by a Saudi-led coalition, have certainly become accustomed to sacrifice.
The United Nations says the conflict there has killed more than 8,000 people, and has warned that 17 million Yemenis -- 62 percent of the population -- are unable to access food. A third of the country's provinces are on the brink of famine, and it is also facing a cholera epidemic.
Several global leaders marked the start of Ramadan with messages urging a peaceful world.
"Islam is the religion of mercy, moderation and peaceful coexistence," King Salman of Saudi Arabia, home to Islam's holiest sites, said in a statement.
US President Donald Trump, winding up his first overseas trip in office that began in Saudi Arabia, wished Muslims a "joyful Ramadan", and urged them to use the holy month to reject extremist violence.
"At its core, the spirit of Ramadan strengthens awareness of our shared obligation to reject violence, to pursue peace, and to give to those in need who are suffering from poverty or conflict," Trump said.
In Indonesia, the world's most populous Muslim-majority country, police used a steamroller to crush thousands of bottles of alcohol, banned under Islam, and torched a huge stash of seized drugs in the run-up to Ramadan.
Soaring temperatures and long days are expected to test the will of those who are fasting in many countries.
Many Ramadan shoppers have complained that rising food prices meant they could not prepare lavish iftar meals as they once did, and would need to save some money to celebrate the Eid al-Fitr festival that follows at the end of the month.