Wait, today is a holiday called “Hallowmas?” What does it mean?

Halloween is actually just the beginning of a string of otherworldly holidays. The tricks, treats and customs of Halloween, now mostly secular, are based in part on an ancient Christian festival that spans November 1st and 2nd.

November 1 is All Saints’ Day, when all saints — known and unknown — are recognized.

(The “een” in “Halloween” ties into these lesser-known occasions. Find out what “Halloween” actually is short for, here.)

The Roman Catholic Church’s official name for All Saints Day is Solemnity of All Saints’ Day, but it is also called Hallows or Hallowmas. (Hallowmas is shortened from Hallow’s mass.) In the Western Christian world, All Saints’ Day is celebrated on November 1. The word hallows is used in multiple ways. It can refer to saints and the relics of saints. It can also refer to the shrines in which the relics are kept.

The day after All Saints’ Day, November 2, is All Souls’ Day. This holiday honors the faithful who have died but have not yet reached heaven. In Mexico and the United States, this occasion is better known as Dia de Los Muertos, or Day of the Dead.