During the memorial festival of Yom Kippur, people commemorate the Day of Atonement by reflecting on their actions over the past year. It involves fasting, prayer, and repentance, as individuals seek forgiveness for their misdeeds from both God and others. The day is marked by a solemn service in synagogues, where communities come together to remember and honor those who have passed. It emphasizes purification, forgiveness, and the importance of self-reflection.