The tradition of wearing scary costumes for Halloween has European and Celtic origins. On Halloween, it is believed that spirits of the dead or ghosts come back to the earth world to visit those they have left behind. People thought that they would encounter ghosts if they left their homes. To avoid being recognized by these ghosts, people would wear masks when they left their homes after dark so that the ghosts would mistake them for fellow spirits.
To keep ghosts away from their houses on Halloween, people would place bowls of food outside their homes to appease the ghosts and prevent them from attempting to enter.
These days, people don’t always wear scary costumes anymore, they can be super heroes, or any other fun costume.