The festival of All Saints, also sometimes known as All Saints' Day, All Hallows or Hallowmas ("hallows" meaning "saints," and "mas" meaning "Mass"), is a feast celebrated in the honour of all the saints, known and unknown. Halloween is the day preceding it, and is so named because it is "The Eve of All Hallows". All Saints is also a Christian formula invoking all the faithful saints and martyrs, known or unknown.