Halloween means Hallows Evening. It is the evening before All Hallows Day (now called All SaintsDay) , a Christian holiday, celebrated on the November 1st.
　　History traces Halloween back to the ancient religion of the Celtics. The Celts were the ancestors of the present-day Irish, Welsh and Scottish people. In the 5th century BC, in Celtic Ireland, summer officially ended on October 31st. On the November 1st, Celtic peoples celebrated the festival of Samhain,which marked the beginning of winter and the Celtic New Year. Celts thouge back and move freely looking for living bodies to possess.