Being of the Christian persuasion I celebrate Palm Sunday.
It is a feast which happens on the Sunday prior to Easter, to which I personally refer to as 'Passover'.
Inasmuch as IMHO "Easter" is derived from the pagan "Ishtar", whom I do not worship I do not use the word Easter as so many others.
The celebrations associaterd with Ishtar included eggs and orgies in the forests — quick like a bunny ...
You get the idea.
So Palm Sunday commemorates the triumphal entry of Christ into Jerusalem on a donkey colt which is mentioned in the books of Matthew, Mark, Luke, and John of the Holy Bible.
Christ was met by throngs of His followers and supporters who lined the road into the city waving branches cut from palm trees.
They laid palm fronds on the road before him along with their cloaks over which Jesus rode upon his humble steed.
This entry into Jerusalem fulfilled the Old Testament prophecies promising that the Messiah would enter the holy city and go to the temple.
Palm Sunday is said to be first day of Holy Week.
My personal interest is that it precludes the following Sunday which represents the "third day" upon which Christ arose from the dead after being crucified by the Romans at the behest of the Sanhedrin.