Ujjnyomok

Ujjnyomok, or fingerprints, are the impressions left by the friction ridges of the fingertips and thumbs. They form in the womb and remain largely unchanged throughout life, except in case of severe scarring. Because their patterns are unique to each person and usually do not duplicate even among identical twins, they are widely used for personal identification.

Most common fingerprint patterns are loops, whorls, and arches, with subtypes such as tented arches and double loops. Within the patterns, minutiae points—ridge endings, bifurcations, short ridges, and dots—provide detailed markers used to compare two prints. The combination of pattern type and minutiae generally yields a unique configuration.

Collection and analysis: In forensics prints are obtained as latent prints, visible prints, or plastic prints. Latent prints are developed with powders or chemical reagents and then lifted for analysis. Digital imaging and automated matching systems, such as AFIS, compare prints against databases. Matching relies on both global pattern and local minutiae; error rates exist and expert examination is required for controversial matches.

History and applications: The use of fingerprints for identification was developed in the late 19th and early 20th centuries, with contributions by William Herschel, Henry Faulds, and Edward Henry, and adoption by police services worldwide. Today fingerprints are used not only in criminal justice but also in biometric authentication for devices and access control, raising privacy and civil-liberties considerations.