Eid al-Adha - which means "feast of the sacrifice" - is celebrated just over two months later, at the same time when many Muslims perform the Hajj pilgrimage.
Muslims believe, therefore, that they are commanded by Allah as mentioned in the Quran to continue their fast until the last day of Ramadan and pay the Zakat-al-Fitr (tithes or almsgiving) before offering as well as celebrating the Eid.
But the date of Ramadan changes year by year because its timing is based on the lunar calendar, which is 11 days shorter than the Gregorian calendar we base our year on.
In London, the sun is due to set on Thursday night at 9.19pm.
When does Ramadan end this year?
The federal government has declared Friday, June 15 and Monday 18, as public holidays to mark this year's Id-el Fitr celebration. Many Muslims also recite the takbir, which is the declaration of faith, on their way to the prayer ground and take part in Zakat al-Fitr (charitable contributions).
There are some exemptions from fasting: you can eat and drink if you are suffering from an illness, travelling, are elderly, pregnant, breastfeeding, diabetic, chronically ill or menstruating.
The festival falls from the 21st of August to the 25th, and celebrates the end of the annual pilgrimage to Mecca.
The festivities of Eid begin only after the crescent moon is seen.