Eid is celebrated on the first day of Shawwal – the tenth month of the Islamic calendar – and depends on the sighting of the New Moon.
The date of Eid al-Fitr can not be predicted with certainty and as the moon is not visible across the world at the same time, the celebration will fall on different dates in different countries.
The exact date varies as it is based on the lunar cycle and depends on when the new moon is spotted.
Muslims in the UK start the day by waking up early and gathering at the local mosque or an outdoor prayer ground for the Eid morning prayers.
The day is usually marked by lavish food and families coming together to celebrate the conclusion of the 29-30 days of dawn to sunset fasting.
In some UK cities, such as London and Birmingham, Muslim communities organise events with various family activities.
The Birmingham gathering is the largest Eid celebration in Europe and last year more than 100,000 Muslims descended on Small Health Park.
On Eid al-Fitr there is a strong focus on charity and Muslims are expected to donate food or money to the poor.
Eid al-Fitr 2018: Muslims will celebrate the end of Ramadan on Friday
Eid al-Fitr 2018: Eid is celebrated with lavish food and families coming together
The underlying purpose of Eid is to thank Allah for the strength he provided to Muslims during the holy month of Ramadan.
Eid al-Fitr is a public holiday in many Muslim countries, but is not a public holiday in the UK.
Gifts and greeting cards are exchanged and children may receive parents on this special day.
Biryani – a spicy meat and rice dish – is particularly popular in the UK on Eid and members of the Afghan community may enjoy bolani – a type of flatbread stuffed with spinach, potatoes, pumpkin or lentils.
Eid al-Fitr 2018: People exchange gifts on Eid
When will the moon be visible in the UK?
There is a lot of confusion over how the date of Eid al-Fitr is decided, as religious authorities in each nation have the right to declare the date according to the sighting of the new moon in their region.
Eid dates can differ around the world, but this is usually within one or two days of each other.
The date of Eid al-Fitr is determined on the sighting of the crescent moon following the new moon.
A new moon was observed in the UK on June 13, and a crescent moon isexpected tonight, June 14.