a holy day in the Catholic Christian calendar set aside to honor all the saints, especially those without their own special feast days. In the West, it is held annually on November 1. Eastern churches reserve the first Sunday following their Pentecostal celebration to commemorate the saints, and the holiday typically falls in the month of June.
It is not known for certain exactly when or how All Saints' Day came to be celebrated. In the East, however, special days for paying tribute to martyrs occurred on varying dates as early as the 4th century AD. On May 13, 609, Pope Boniface IV dedicated the Pantheon in Rome to the Virgin Mary and all the Christian martyrs, and observances marking that date began the following year. In the early 8th century, Pope Gregory III expanded the holiday to include all saints and dedicated to them a chapel in St. Peter's Basilica in Rome. He also moved the celebration to November, perhaps in an effort to supplant the pagan festival of the dead known as Samhain. All Saints' Day began appearing in the church calendar in the 9th century during the reign of Pope Gregory IV.
Today many people mark the occasion by bringing flowers to cemeteries and cleaning the graves of deceased loved ones. In the Philippines, unexplained illnesses are often said to be caused by failure to remember a relative's tomb. In countries such as Bolivia and Mexico, it is common for special tables or altars to the dead to be set up in homes and for feasts to be prepared.
Roman Catholics throughout the world attend mass on All Saints' Day because it is a holy day of obligation. In the United States, in the state of Louisiana (which has a large Roman Catholic population), November 1 is a legal holiday.