Fingerprints patterns are of three types: arches, loops and whorls, and loops are the most common pattern, being found in 65 to 70 percent of all fingerprints. In this pattern, ridges or curved lines enter from one side of the finger, form a loop and exit from the same side.
Loops have one delta, a point in the triangular space created by diverging ridges. There are two kinds of loops based on the direction of their openings: ulnar and radial. Radial loops, often found in the index finger, open towards the thumb. They are not as common as ulnar loops, which open towards the little finger. Whorls and arches are found in 25 to 35 percent and 5 percent of fingerprints, respectively.