Fingerprints. Computer illustration of coloured fingerprints. Fingerprints are individual for every person. Even identical twins have different fingerprints. They are classified by the shapes of their raised ridges. The four main classifications of pattern are: loops, whorls, arches and combina- tions of these. Loops, such as the ulnar loop at lower left, form 70% of fingerprint patterns. Whorls (as at lower right) form 25% and arches 5%.