Halloween originated with the ancient Celts, who believed the souls of the dead visited Earth on October 31st. The Romans later invaded Europe and spread the tradition of celebrating at this time. Key Halloween traditions include carving jack-o-lanterns from pumpkins, lighting bonfires to scare away evil spirits, and dressing up in costumes to avoid being recognized by ghosts. Many superstitions also developed, such as finishing travels before sunset or using candles to divine the future.