Many dressed up as souls of the dead and were understood to be protecting themselves from the spirits by impersonating them. More about that below.
The Christian origin of the holiday is that it falls on the days before the feast of All Hallows, which was set in the eighth century to attempt to stamp out pagan celebrations. Christians would honour saints and pray for souls who have not yet reached heaven.
They went dressed up as angels, demons or saints. The soul cakes were sweet, with a cross marked on top and when eaten they represented a soul being freed from purgatory.