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.
In Austria some people leave bread, water and a lighted lamp on the table before going to bed. It is believed that this will welcome dead souls back to Earth.
By the 11th century, this had been adapted by the Church into a tradition called souling, which is seen as being the origin of trick-or-treating. Children go door-to-door, asking for soul cakes in exchange for praying for the souls of friends and relatives.