"Drifting" in the sense of driving like a retard/thrashing your car is a mis-translation of a Japanese pastime of hanging the ass end of a car out to look cool. The actual term "drift" is when the slip angle of all 4 tires is the same a.k.a. neutralsteer. Of course now this begs an explanation.

Slip angle - the difference between the direction a tire is pointed and the direction the car is traveling.

Understeer - the slip angle of the front tires is greater than the rear tires; also called "pushing."

Oversteer - the slip angle of the rear tires is greater than the front tires; also called "hanging the ass end out."

Neutralsteer - all four tires are sliding at the same slip angle; a true "drift" and also the fastest way through a corner (assuming you're on a non-limited-traction surface like a paved road).

You can get any car to understeer, oversteer or neutralsteer. It's easier to get a FWD car to understeer because power can be used to break the front tires loose and increase their slip angle. Oversteer is easier to get in a RWD car for the same reason. AWD cars don't necessarily neutralsteer because they're not always splitting power 50/50 front-rear and because the amount of weight and stiffness of suspension is not generally tuned to encourage neutralsteer.

For a more detailed explanation (which will also make you much much smarter ) check out http://www.turnfast.com/tech_handling/handling.lasso and at the very least read the sections on tire traction and weight transfer.

OK, I'll get off my soapbox now.