It marks the end of Summer and the beginning of Winter. In the past, Samhain was a festival for the time between the old year and the new year. It was a time for having bonfires and playing tricks. It was also thought a time when people could make contact with departed loved ones and foretell the future. Today some people have special ceremonies on this day.
Some people have parties and other people have special dinners.
One interesting dinner dish is called Colcannon. This dish is made of potatoes and cabbage. Items are put in the dish that are thought to tell the future. The following recipe came from the Turning The Wheel site. Stir occasionally until warm then add fortune items.