Chalking the door is a Christian Epiphanytide tradition used to bless one's home, which originated in medieval Europe. Epiphany Either on Twelfth Night (5 January), the twelfth day of Christmastide and eve of the feast of the Epiphany, or on Epiphany Day (6 January) itself, many Christians (including Anglicans, Episcopalians, Lutherans, Methodists, Presbyterians and Roman Catholics, among others) write on their doors or lintels with chalk in a pattern such as "20 ✝ C ✝ M ✝ B ✝ 25". The numbers in this example refer to the calendar year 2025 and the crosses to Christ. The letters C, M, and B stand for the traditional names of the biblical Magi (Caspar, Melchior and Balthazar), or alternatively for the Latin blessing Christus mansionem benedicat ('May Christ bless this house'), or IIIK referring to the three kings. Chalking the door is done most commonly on Epiphany Day...