Although Good Friday and Easter Sunday might be more well-known, today's holiday — known as Holy Thursday, Maundy Thursday, Sheer Thursday, and even the Thursday of Mysteries — marks the beginning of the three-day Easter celebration.
The holiday commemorates the last supper Christ enjoyed with his disciples, four days after His triumphal entry into Jerusalem on Palm Sunday. It is in fact one of the oldest celebrations of the Holy week, as it commemorates the institution of three pillars of the Catholic faith: the Sacrament of Holy Communion, the priesthood, and the Mass.
More from GlobalPost: Pope Benedict condemns dissident priests
How do people around the world celebrate the Thursday of Mysteries?
Although many Catholics engage in common practices to celebrate the day, including reenacting the passion and the crucifixion, others have their own unique time-honored traditions.
Some Catholics practice their own "Christian adaptation" of the Passover Seder, in order to better understand the history of the holiday.
At church, the traditions are a bit different as well. People engage in a ritual of washing their feet, to mimic Jesus washing the feet of his disciples.
Others have adopted their own unorthodox customs.
The Queen will be taking part in today's most well-publicized celebration; she is handing out so-called Maundy Money to pensioners in York. Joined by the Duke of Edinburgh, the Archbishop of York, and Princess Beatrice of York, the Queen will hand out two purses to each pensioners; a red one, which contains a £5 coin commemorating The Queen's Diamond Jubilee and a newly minted 50p coin, and a white one, which contains uniquely minted silver Maundy Money.
Traditionally, the gifts are given to pensioners from one diocese each year. However, this year is different; 86 women and 86 men, one commemorating each of the Queen's 86 years, will receive the money in recognition of their services to the Church and their communities.
More from GlobalPost: Meet Volker Kraft, the man of 10,000 Easter eggs
Germans celebrating the holiday eat a traditional dish called Gründonnerstagssuppe — a green soup made of spinach, parsley, green onions, cucumber and dill. Green foods specifically are eaten because of the, "close association [of the word green] to the German word for "grief" or "weeping." Many families would eat only green vegetables, spinach in particular, as a way of humbling themselves before God.
In central Brazil, in Cidade de Goias, penitents attend the "Procession of the Torches," in which hooded figures carry torches lit on fire.
Some celebrate in more zealous and drastic ways. In Manila, a handful of Catholics engage in brutal self-flagellation to atone for their sins.
More from GlobalPost: Italy to tax Vatican for commercial properties
Know any unique Maundy Thursday celebrations? Have any of your own? Share them in the comments section below.