Modern Jews call the Day of Atonement "Yom Kippur" and regard it as the holiest day on their calendar. On Rosh Hashanah, it is believed that God writes a "book" of each person's actions during the past year. Eight days later, on Yom Kippur, these "books" are irrevocably sealed. The eight days known as "Days of Awe," are a time to repent and be cleansed from sin, and thus to alter the judgments inscribed in the "books." During this time, many Jews wear white as a symbol of purification. It took place around September of October, in between the Feast of Trumpets and the Feast of Tabernacles in the seventh month of the Jewish year.
On the Day of Atonement, the high priest washed carefully, put on special garments, and made sin offerings for himself and the community. He sprinkled atoning blood throughout the tabernacle area and publicly confessed the sins of the nation. The people were required to rest and fast. They were to "deny" themselves in the sense of humbling themselves before the Lord about their sin.
Today in the Word, July 2003, p.23