These days Halloween is not usually considered a religious holiday. It is primarily a fun day for children. Children dress up in costumes like people did a thousand years ago. But instead of worrying about evil spirits, they go from house to house. They knock on doors and say "trick or treat." The owner of each house gives candy or something special to each trick or treater.
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.
Gaels would also offer food and drink, and light bonfires to ward off the evil spirits.