
Laptops, with repeated exposure to skin, can lead to something called "toasted skin syndrome." So while it may seem natural and normal to prop up your computer on your legs while you use it, you may want to change that habit.
In a recent case, reported on by Associated Press, a 12-year-old boy got a sponge-patterned discoloration on his thigh after playing computer games repeatedly for hours over the span of several months.
Another case was a law student that went to the doctor to find out about her skin's discoloration. The student had spent more than six hours a day using her laptop computer on her lap. While in use, the laptops temperature can rise up to 125 degrees.
Toasted skin syndrome can also be cause by the overuse of heat sources that aren't quite hot enough to cause burns. The syndrome doesn't lead to any major health issues aside from permanent skin darkening.