The basic types of fingerprints are bucket pattern, bow pattern, skip pattern and hybrid pattern. Fingerprints have different shapes due to the different pressing directions of subcutaneous tissue on the finger belly epidermis. Bow pattern is mainly composed of two systems, bow and horizontal, which are stacked up and down. The upper part of the dustpan pattern and the periphery of both sides are wrapped by more bow lines. The bucket pattern is composed of three systems: wavy line and horizontal line. Type of fingerprint fingerprint is the pattern formed by concave convex skin on the finger abdomen at the end of human fingers. In a narrow sense, fingerprint refers to the mastoid line pattern on the skin of the first palm of human fingers. In a broad sense, fingerprint includes finger print, knuckle print and palm print.
It seems that fingerprints can increase the friction when the hand contacts the object. In fact, they reduce the friction, make the skin easier to stretch and deform, and avoid skin injury. （ZhiWenDeLeiXing）