Arafat day (يوم عرفة) falls on the ninth day of Dhu Al Hijja (ذو الحجة) according to the hijri calendar.

By Al-Jazeera English on flickr

Taking place roughly 70 days after the end of Ramadan, Arafat Day marks the second day of pilgrimage (الحج).

The occasion marks the day when a verse of the Quran revealed that Islam was perfected, and when Allah’s blessings were completed.

“This day have I perfected for you your religion and completed My favour to you and chosen for you Islam as a religion.”

(Surah Al Maidah – Verse 3)

قال الله تعالى : ( الْيَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي وَرَضِيتُ لَكُمُ الْإِسْلَامَ دِينًا ) المائدة/3

Mount Arafat is the site where Prophet Mohammad (PBUH) spoke his Farewell Sermon.

Arafat day occurs the day before the start of Eid Al Adha (عيد الأضحى).

At dawn on Arafat Day, Muslims travel from Mina to Mount Arafat, which is just outside of Makkah. They will remain on Mount Arafat until Maghrib prayers. The distance between Mina and Mount Arafat is about 20km.

Those who are unable to travel to Makkah for haj may fast instead.

Afara day has special supplications that pilgrims repeat

Adapted from (http://gulfnews.com/guides/life/community/what-is-arafat-day-1.1585593)