Human fingertips are probably the most sensitive skin area in the animal world. They can feel the difference between a smooth surface and a pattern embedded only to a depth of 13 nanometers.
This is due to the bulging of the epidermis on the surface of the fingertips, which allows one to distinguish between various textures, materials, temperatures and pressures.
Friction caused by the movement of a fingertip along a surface or material stimulates mechanoreceptors and then transmits tactile information to the brain. If we compare our fingertips to the earth, then we can feel the difference between a one-story house and a car.