Eid al-Adha' (Arabic: عيد الأضحى‎ ‘Īd al-’Aḍḥá, IPA: [ʕiːd al ʔadˁˈħaː], "feast of sacrifice") or "Festival of Sacrifice" or "Greater Eid" is an important religious holiday celebrated by Muslims worldwide to commemorate the willingness of Abraham (Ibrahim) to sacrifice his son Ishmael (Isma'il) as an act of obedience to God, before God intervened to provide him with a sheep to sacrifice instead.

Eid al-Adha is the latter of two Eid festivals celebrated by Muslims, whose basis comes from Sura 2 (Al-Baqara) Ayah 196 in the Qur'an. Like Eid ul-Fitr, Eid al-Adha begins with a Sunnah prayer of two Raka'ah (units) followed by a sermon (khuṭbah).

The word "Eid" appears in Sura al-Mai'da ("The Table Spread," Chapter 5) of the Qur'an, meaning 'solemn festival'.

Eid al-Adha is celebrated annually on the 10th day of the 12th and the last Islamic month of Dhu al-Hijjah (ذو الحجة) of the lunar Islamic calendar. Eid al-Adha celebrations start after the Hajj, the annual pilgrimage to Mecca in Saudi Arabia by Muslims worldwide, descend from Mount Arafat. The date is approximately 70 days (2 Months & 10 days) after the end of the month of Ramadan, i.e. Eid-ul-Fitr. Ritual observance of the holiday lasts until sunset of the 13th day of Dhu al-Hijjah.

Eid-ul-Fitr, Eid al-Fitr, Id-ul-Fitr, or Id al-Fitr (Arabic: ‎عيد الفطر ‘Īdu l-Fiṭr), often abbreviated to Eid, is a Muslim holiday that marks the end of Ramadan, the Islamic holy month of fasting (sawm). Eid is an Arabic word meaning "festivity", while Fiṭr means "breaking the fast". The holiday celebrates the conclusion of the 29 or 30 days of dawn-to-sunset fasting during the entire month of Ramadan. The first day of Eid, therefore, falls on the first day of the month Shawwal. This is a day where Muslims around the world try to show a common goal of unity. It is a day of recognizance of Allah.

Eid-ul-Fitr has a particular salah (Islamic prayer) consisting of two raka'ah (units) and generally offered in an open field or large hall. It may only be performed in congregation (Jama’at) and has an additional extra six Takbirs (raising of the hands to the ears while saying "Allah-u-Akbar" [God is Great]), three of them in the beginning of the first raka'ah and three of them just before ruku' in the second raka'ah in the Hanafi school. This Eid ul-Fitr salah is, depending on which juristic opinion is followed, Fard (obligatory), Mustahabb (strongly recommended, just short of obligatory) or mandoob (preferable).