The name "Loy Krathong" can be translated as "to float a basket", and comes from the tradition of making krathong or a buoyant, decorated basket, which is then floated on a river.
Loy Krathong takes place on the evening of the full moon of the 12th month in the traditional Thai lunar calendar. In the Western calendar this usually falls in November. The traditional krathong are made from a slice of the trunk of a banana tree or a spider lily plant. Modern krathongs are more often made of bread or Styrofoam. A bread krathong will disintegrate after a few days and can be eaten by fish. Banana stalk krathong are also biodegradable, but Styrofoam krathongs are sometimes banned, as they pollute the rivers and may take years to decompose. A krathong is decorated with elaborately-folded banana leaves, incense sticks, and a candle. A small coin is sometimes included as an offering to the river spirits.
On the night of the full moon, Thais launch their krathong on a river, canal or a pond, making a wish as they do so. The festival may originate from an ancient ritual paying respect to the water spirits.
I shot a video ( about 2 minutes) of the celebration at the University next to our Condo. You have to go to Facebook to see it. It is too large for my Blog. https://www.facebook.com/jaylois.meeker
Also I found a 13 minute You tube Video if you want to know more about Loy Krathong Festival