Eid al-Adha
Eid al-Adha (Id ul-Adha) is an Islamic festival falling on the 10th day of the month of Dhul Hijja (Thou al-Hijja) to commemorate the willingness of Ibrahim (Abraham) to sacrifice his son.
Elsewhere on timeanddate.com
Labor Day / May Day
Labor Day, International Workers' Day, and May Day, is a day off for workers in many countries around the world.
AM and PM Explained
How does the 12-hour clock system work? Is midnight 12 am or 12 pm?
Daylight Saving Time (DST)
Why do many countries set the clocks back and forth an hour twice a year?