OK, so you know that laser hair removal involves a laser (obviously), but how exactly does that laser leave your skin smooth and stubble-free? "Hair removal lasers target pigment, both in the cells at the base of the hair follicle and in the hair itself," explains board-certified dermatologist Arielle Kauvar, M.D., founding director of New York Laser & Skin Care. "The heat from the laser then destroys or damages only the hair follicle, without harming any of the skin nearby." Once the follicle is gone, so too is the hair that would normally grow from it.

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Technically, yes. "The medical definition of 'permanent' hair removal is achieving at least a 90 percent, long-term reduction in hair growth," says Kauvar. IRL, however, your results may be slightly different: "It's important to have realistic expectations about laser hair removal," points out cosmetic dermatologist Paul Jarrod Frank, M.D. "What that means for most people is anywhere from an 80 to 95 percent reduction of hair."

And yes, at some point down the line, you may need a touch-up or two. While the laser will damage some hair follicles completely, inevitably some will only be damaged slightly, and certain factors -- age, hormonal changes -- can trigger new hair growth, explains Frank. Sometimes the laser damages the follicle so that instead of producing a terminal hair, which is thick and coarse, it produces a vellus hair, which looks like peach fuzz, adds Kauvar, and those may also become noticeable. At the end of the day, there's no denying that laser hair removal is the most permanent option out there, but, as it goes in life, nothing lasts forever; it's possible that even on totally treated areas a hair or two may still sprout up.

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Because hair removal lasers work by targeting hair's pigment, the best candidates are those who have a lot of it of it, i.e. dark hair, though there also needs to be contrast between the hair and the skin, explains Kauvar. So, basically, anyone with light skin and dark, coarse hair -- coarse strands contain more pigment than fine ones -- is the ideal candidate and can expect the best results. That being said, technology advancements and all kinds of new lasers mean that it can also be done on anyone with dark skin or finer, lighter, hair; just keep in mind that the results may not be quite as successful, so manage your expectations accordingly, recommends Frank. (See our story on laser hair removal for dark skin here.)

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"Any place on the body where hair grows can be treated," says Kauvar. This includes arms, legs, underarms, bikini line, and even the face; the upper lip is one of the most common treatment stops, according to Kauvar. The only spot that's off limits is your brows, since the types of lasers used are too powerful to be used near your eyes. When deciding which area to zap, you may also want to consider that this will impact the final price, more on that to come.

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If we're talking real tan, the answer should always be no (the ensuing skin damage is so not worth it), but it's even more of a no-no in this instance. "If you're naturally fair-skinned but go in for your appointment with a tan, there will be less contrast between the color of the skin and the color of hair, and the laser may not be as effective," notes Frank. It's a good idea to skip self-tanner, too, just to be safe, as there's a chance the laser could pick up some of that color as well, he adds.

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