Ī friction ridge is a raised portion of the epidermis on the digits (fingers and toes), the palm of the hand or the sole of the foot, consisting of one or more connected ridge units of friction ridge skin. Fingerprint matching considers only the obvious features of a fingerprint. The matching of two fingerprints is among the most widely used and most reliable biometric techniques.
Deliberate impressions of entire fingerprints can be obtained by ink or other substances transferred from the peaks of friction ridges on the skin to a smooth surface such as paper. Moisture and grease on a finger result in fingerprints on surfaces such as glass or metal.
The recovery of partial fingerprints from a crime scene is an important method of forensic science. A fingerprint is an impression left by the friction ridges of a human finger.