A flattop is a type of very short hairstyle similar to the crew cut, with the exception that the hair on the top of the head is deliberately styled to stand up (typically no more than an inch) and is cut to be flat, resulting in a haircut that is square in shape. It is most often worn by men and boys, particularly those in the military and law enforcement in the United States.
The haircut is usually done with electric clippers to cut the side and back hair to or near the scalp, and then more intricate cutting is done on the top hair to achieve a level plane. When cutting a new flattop, the top hair is usually cut to about an inch long, then blow-dried to stand up straight, and then finally cut with clippers and scissors to achieve the final look. Wax can be used to stiffen the front of the flattop.
Because the shape of a flattop is, by definition, not compatible with the round shape of a human head, there is often a spot on the very center of the top that is buzzed shorter to achieve a flat surface, almost to the point of being shaved. This area is called the "landing strip," because this area of the head with shorter hair resembles a grassless aviation landing area.
Because the haircut is so short and quickly grows out of its precisely-cut shape, maintenance haircuts are required at least every few weeks, and many flattop wearers get haircuts as often as once a week.