Muslims celebrate two major religious festivals every year. One is Eid ul-fitr and the other is Eid ul-Adha. Eid-ul-fitr is celebrated on first of Shawal after fasting in the month of Ramadan. Special Eid prayers after sunrise are offered in open areas on both of the occasion. After the prayers, the Muslims greet each other and celebrate the whole day.

Eid ul-Adha is the greatest event when millions of Muslims gathered at Arafat at the time of Hajj to bow before Allah. After prayers and greeting each other Muslims offer a sacrifice of a camel, a goat, a sheep or a cow to honors the sacrifice of the prophet Hazrat Ibrahim (A.S). The meat is usually divided into three parts, one for the poor, one for the relatives and one for the family.

Difference From Solar Year

Since both of these Eids are celebrated according to Hijri calendar which is based upon the movements of moon around the earth so their comes a difference of about 10 or 11 or may be 12 days due to the difference of the movements of moon and sun according to earth. For example if in year 2016 A.D. Eid ul-Adha was celebrated on 13th of September then the next Eid coming in the year 2017 A.D. will be celebrated on 1st or 2nd of September.

Background

Muslims celebrate Eid-ul-Adha in the remembrance of Prophet Hazrat Ibrahim (A.S) who was ready to sacrifice his own son Hazrat Ishmael (A.S). Hazrat Ibrahim (A.S) was required to prove his love of God by giving up anything which was dearest to his heart i.e. his son Hazrat Ishmael (A.S). He was ready to sacrifice his son but God gave him sheep to sacrifice. The sacrifice made by Muslims of an animal like goat, camel, sheep or cow etc. is to pay tribute to the Prophet Hazrat Ibrahim (A.S).
Importance

The underlying importance of this festival is the spirit of altruism. This festival is celebrated in the remembrance of the great act and strong faith of Hazrat Ibrahim (A.S) and Hazrat Ishmael (A.S).

Eid ul-Adha is a time when Muslims pray for forgiveness from God and in return forgive each other releasing any kind of ill feelings towards others. It also promotes the feelings of Muslim brother hood, sympathy and positive feelings towards people who are less fortunate than our selves.