Eid is when Muslims participating in fasting during the holy month of Ramadan break their fast at the end of the holy period.
The daily fasting undertaken by Muslims means they must fast during the hours of sunrise to sunset, and pray and read the Koran during that time.
They can then break their fast at sunset, called Iftar, and replenish themselves.
People actively practising Islam will have repeated this daily fasting ritual for the entire month of Ramadan, which is the ninth month of the Islamic calendar.
Ramadan began this year on Friday May 26, and will end Sunday June 25, which is know as Eid al-Fitr.
For Muslims honouring Ramadan in the UK, this year has been particularly hard- fasting for the longest day of the year and fasting through a heatwave.
Those who are sick, travelling, elderly, pregnant or breastfeeding do not have to partake in Ramadan.
Eid al-Fitr is celebrated by Muslims worldwide and is the festival that marks the end of Ramadan.
The celebration will begin the evening of Sunday, June 25 and ends the evening of Monday, June 26 in the UK and Europe.
The exact date of the end of Ramadan is determined by the sighting of the new moon.
Meaning dates and time differ throughout the world when Eid al-Fitr starts.
Eid Mubarak means ‘blessed celebration’ and so Muslims will greet each other by saying ‘Eid Mubarak’ to wish each other a blessed Eid.
Eid al-Fitr (Eid ul-Fitr) is aptly named meaning ‘breaking of the fast’.
You may also hear people saying ‘Eid Mubarak’ on Eid al-Adha which is the festival of the sacrifice and is seen to be more sacred than Eid al-Fitr.
Eid al-Adha will begin on the evening of Friday, September 1 and ends on the evening of Tuesday, September 5.
This festival is also determined by the Islamic lunar calendar and lasts four days.
Eid al-Adha is the only other Muslim holiday that is celebrated worldwide each year and is considered holier than Eid al-Fitr.
The celebration honours the willingness of Ibrahim to sacrifice his son to show his submission to Allah’s command.
The Islamic prophet Muhammad originally said Eid al-Fitr was a time when Muslims give their thanks to Allah and give money to the poor.
Muslims will gather in Mosques on Eid al-Fitr to say Salat, the Eid prayer, afterwards there will be celebrations and sharing of food.
Eid festivities can last for three days in some places.
Muslims are not allowed to fast on Eid al-Fitr, the only day of the year they are prohibited from fasting.
The most important day in the Muslim calendar is a national holiday in Muslim countries and a petition has been stated to make it so in the UK.
Mayor of London, Sadiq Khan, has invited everyone, regardless of faith, to join in the Eid Festival 2017 at Trafalgar Square on July 2.