The festival ends weeks of fasting, and is one of the most important events in the Muslim calendar.
Its exact start varies from country to country based on moon sightings, but people have been celebrating with feasts and family.
This year, however, Ramadan was marred by major attacks in Saudi Arabia, Bangladesh, Turkey and Iraq.
Saudi Arabia was hit by three suicide attacks on Monday, including one near Islam's second holiest site. Sunday's Islamic State-claimed bombing in Iraq killed 165 people.
Here is how the end of Ramadan, and the start of Eid looked around the world.
Muslims around the world have been celebrating Eid al-Fitr, which marks the end of the holy month of Ramadan.