What is the Red Ring of Death on the Xbox?

im planning on getting an xbox but many ppl r talking about the red ring of death and i have no idea bout wat it is or wat it does?

Suggestion:

The Red Ring of Death is when there is 3 red rings flashing and it means something is wrong with the hardware or the power supply. The new xbox 360 Slim is suppose to prevent that from happening. Btw its not a big deal to me.