We hear about the dangers of Christmas trees -- especially real ones -- bursting into flames every year at Yuletide. Yet neither real nor artificial Christmas trees are that likely to catch on fire. First, real trees simply don't spontaneously combust, even if you forget to water them. And secondly, actual cases of any Christmas trees causing residential fires are extremely rare. According to the National Fire Protection Association (NFPA), between 2005 and 2009, U.S. fire departments responded to an average of 240 home fires per year that began with Christmas trees [source: National Fire Protection Association]. With tens of millions of trees both fake and real sold every year, 240 fires is a pretty small percentage. Of course, this doesn't mean you should take unnecessary risks. If you have a real tree, water it regularly, and remember to turn off the lights when you're away. And remember that overloaded outlets and faulty wires are the biggest potential culprits when it comes to holiday fires [source: National Christmas Tree Association].