SEY-fer Chai-IM is the Book of Life. It is said that all of our deeds are weighed and judged. On Rosh Hashanah the book is opened. From the month leading up to Rosh Hashanah, Elul, all the way up to the final moments of N'ilah, the closing of the Yom Kippur service, we pray and do T'shuvah so that we may be inscribed in the book of life.