Eid Mubarak to all readers of TTP.
Eid el-Adha is a religious festival and observance celebrated by Muslims as a commemoration of Abraham's willingness to sacrifice his son Ismael for God (Allah in Arabic). It is one of two main festivals celebrated by Muslims celebrate, and it generally begins with a short prayer followed by a sermon. The celebrations last for four days.
The festival starts on the 10th day of the month of Dhul Hijja of the lunar Islamic calendar. This is the day after the pilgrims in Hajj, the annual pilgrimage to Mecca in Saudi Arabia by Muslims worldwide, descend from Mount Arafat.
This year, it's observed on December 20...so the main religious observances of the three great Abrahamic traditions have converged this year within a few weeks of each other.