Triskaidekaphobia is the fear of the number 13. This superstition is common in many cultures, where the number is often associated with bad luck or misfortune. Some people believe that the fear stems from historical events, such as the Last Supper, where Judas Iscariot, the betrayer of Jesus, was the 13th guest. Due to this fear, some buildings skip the 13th floor, labeling it as the 14th instead. Additionally, many people avoid scheduling important events on the 13th day of the month, especially if it falls on a Friday, which is often considered an unlucky day in various cultures.