By the will of Allāh (subḥānahu wa taʿālā), Muslims across the world celebrated ‘Eid al-Adhā. It began on the tenth day of Dhul Hijjah in the twelfth month of the Hijri calendar (Islamic Calendar).
According to some scholars this is the best day of the first ten days of Dhul Hijjah which are known to be the best days of the entire year. Some scholars even say that it is better than the day of ‘Arafah. The Prophet (sall Allāhu ʿalayhi wa sallam) said that:
“The greatest day in Allah’s sight is the day of sacrifice…” 
The Prophet (sall Allāhu ʿalayhi wa sallam) also said that it is the greatest day of Hajj, as reported by al-Tirmidhi.
‘Eid al-Adhā which translates to the “Feast of Sacrifice” is the second of the two ‘Eid’s prescribed to Muslims and also known as ‘Eid al-Akbar, the great ‘Eid. The day commemorates the willingness of Ibrahim (ʿalayhi al-Salām) to sacrifice his own son at the command of Allāh (subḥānahu wa taʿālā).
Imām Ibn al-Qayyim (Rahimahullāh) states that: “The purpose was not for Ibrahim (ʿalayhi al-Salām) to kill his son rather it was to sacrifice him in his heart so all love belonged to Allāh alone.” 
The day is marked by carrying out udhiyah which refers to the act of slaughtering an animal (a camel, cow, sheep or goat) for the sake of Allāh on the 10th of Dhul-Hijjah. In fact, ‘Eid al-Adhā, the main festival of Islām, is named as such because of this act. The word udhiyah also refers to the animal either before it is sacrificed or after it is sacrificed. 
Udhiyah is a very noble social act as the sunnah is to give part of it as charity, a part of it as a gift, and a part of it is to be consumed by the one sacrificing and his/her family. Some people in poor countries do not eat meat throughout the year due to its expensive nature except when they receive udhiyah.
Muslims across the globe came together at Masjids and open spaces in large number in order to offer the ‘Eid prayer and celebrate the occasion.
The ‘Eid also comes as Muslims across the globe travelled to Hejaz to perform the Hajj. According to the General Authority for Statistics (GASTAT), this year the total number of pilgrims reached 2,371,675 pilgrims, 1,758,722 of whom came from outside Hejaz and 612,953 from within. 
We would also like to take this opportunity to thank all of you who have donated generously to support the work of Islam21c. Alḥamdulillāh with the help of Allāh and your support we have almost been able to reach our £10,000 target this Dhul Hijjah. For all those who missed out and have not had the chance you can still contribute! End ‘Eid in the best way and give charity now by making a donation to Islam21c here.
We pray that Allāh (subḥānahu wa taʿālā) bestows the Muslims across the globe a safe, secure and blessed ʿEid. May Allāh (subḥānahu wa taʿālā) have mercy on those who are suffering, grant them patience, victory and bring them justice in the Dunya and Ākhira, Āmīn.
Notes: Sunan Abi Dawud  الجواب الكافي لمن سأل عن الدواء الشافي  https://www.islam21c.com/islamic-law/3657-faq-all-about-dhul-hijjah-sacrifice-udhiyah-part-2/  http://english.alarabiya.net/en/News/gulf/2018/08/12/Latest-statistics-show-over-1-3-mln-pilgrims-have-arrived-in-Saudi-Arabia.html