Taoist Chinese believe that during the seventh month of the lunar calendar the “Gates of Hell” are opened and souls of the dead are freed and allowed to roam the earth. The 15th day of this month is the height of the celebration.
The Hungry Ghost festival is different from Chinese ancestor worship because 1) the ghosts are coming to you, rather than you going to visit a grave and 2) all ghosts are involved, not just your ancestors, so there are stranger ghosts to deal with.
So how does one interact with these freed ghosts? By feeding them, holding shows for their entertainment, burning joss sticks or joss paper, which is a symbolic way of giving them money and other material goods they may need.
When we walk home from the subway we can see the offerings out in full force: (I don't take pictures of people who are actually burning, but when we walked by and the area was empty, we snapped a few.)
It was a huge mess, but there are lots of people trying to appease lots of ghosts, so I guess that makes a mess. People buy multiple grocery bags full of joss sticks and joss paper to burn. And while all of that goes up in smoke--or ash, rather--the plastic bags and the packaging were lying all over the grass.
In order to be respectful of those of us that are not worried about ghost appeasement, Singapore provides the drums to burn the offerings in, so generally this is limited to a specific area.
And they do a good job of cleaning up between days and after the big event. The drums are still there, but the lawn was cleared the next day.
The money and "things" burned are paper or papier mache (an iPad for the ghosts?). I snagged this example that had blown away from the fire into the bushes near the sidewalk.
If this is worth 50 million, there's no telling how many quadrillion are burned.
The food, however, is real. Here we have oranges, apples, packages of candies, and some cakes. I don't know what the leaves are. Tea maybe?
And if you can see, the joss sticks are lining the sidewalk (with the white, skinny ash on the grass beside them). They are sparkler sized, and make walking across the grass challenging.
And on top of all of this, there are musical performances, stand up comedy routines, puppet shows, operas, concerts, and other events held in the ghosts' honor, usually on stages set up outside for the occasion. Anyone is welcome to watch the show, but don't sit in the red chairs in the front. Those are reserved.