Bonn Pchum Ben is the festival held for commemoration of the spirits of the dead. The highlight is on the 15th day of the waxing moon during the tenth month of the Khmer calendar, called Pheaktrobotr.
The festival does not just begin and end on one day. In fact, it lasts 15 days, each of which is called a day of Kan Ben. A Ben is an offering. During the first 14 days, people take turns offering food to the monks of their local pagoda in the hope that their offering will reach the souls of their ancestors by virtue of the monks’ sermons.
See a video of Phum Ben in Kampong Speu: