Physiologically, a fingerprint is a structure that appears as pattern of papillary ridges formed by the dermal papillae that lie beneath them. A papillary image is a pattern unique to each individual, developed before birth, which does not change with age and rebuilds itself after damage.
Palm vein patterns are unique to each person and research has shown that these patterns remain unchanged as an individual ages. Palm vein patterns are more complex when compared to fingerprints or the finger vein patterns and have more unique features on which to base matches. This allows for the construction of extremely precise digital models, which can be used for the identification of users whose patterns are collected in large databases. The inner side of the hand is used for identification since it is less prone to changes in skin color than the outside, since it receives less exposure to the sun.