Sometime between mid-September and mid-October each year, Cambodian life slows down in observance of Pchum Ben, one of the most important holidays in the Khmer religious calendar. The holiday lasts for fifteen days, during which time Cambodians gather at pagodas (wearing white, the Cambodian color of mourning) to remember ancestors. During the 15 days of Pchum Ben, the line between the living and dead is thought to be at its thinnest—Cambodians believe that during Pchum Ben, spirits come back in search of living relatives, hoping to atone for sins from their past life.
Like in China, the spirits who wander through the world of the living are thought of as "hungry ghosts," and as such, are offered food and drink to help placate their otherworldly suffering. Cambodians carry food to pagodas, which Buddhist monks then offer to the souls of the deceased.
Because Pchum Ben is such an important holiday—one that nearly every Cambodian participates in—visitors can see rituals and festivities in any Cambodian city. But since Pchum Ben is first and foremost a religious holiday, it's important to observe certain requirements, such as wearing white and avoiding tank tops, shorts or clothing that might be deemed disrespectful.