The Geminids is the king of the meteor showers. It is considered by many to be the best shower in the skies, producing up to 120 multicolored meteors per hour at its peak (depending on your location). It is produced by debris left behind by an asteroid known as 3200 Phaethon, which was discovered in 1982.
The shower runs annually from December 7-17. Its peaks this year will be on the night of the 13th and morning of the 14th of December. Unfortunately, the waxing gibbous moon will block out some of the meteors this year, but the Geminids are so bright and numerous that it should still be a good show. Best viewed from a dark location after midnight. Meteors will radiate from the constellation Gemini, but can appear anywhere in the sky.
As you may know, most meteor showers come from comets. Ultimately, these comets spew forth a plethora of meteoroids and give us a beautiful night of shooting stars. However, the Geminids are a bit different. The parent of this shower is not a comet. Rather, it is created by an odd object that has been designated "3200 Phaethon" (pretty name, huh?). This object sheds very little dusty debris. Ultimately, it does not give off nearly enough to explain the Geminids.
Yet, out of all the debris streams that the Earth passes through each year, the Geminids is the most massive. When we add up the amount of dust in the Geminid stream, it outweighs other streams by factors of 5 to 500. "We just don't know," says NASA astronomer Bill Cooke. "Every new thing we learn about the Geminids seems to deepen the mystery."
So for the time being (until we have more information), just go outside, look up, and enjoy the mystery.