ArchRidges enter on one side and leave on the other. They rise in the center.
LoopRidges enter on one side and curve back. They leave on the same side.
WhorlRidges run in circles or a spiral around a central point.
Core, delta and ridge details 8
CoreThe center of the pattern, on the innermost ridge that turns back.
DeltaThe three-cornered spot where ridges from three directions meet.
RidgeA raised line of skin. Ridges print as the dark lines.
FurrowThe groove between two ridges. Furrows leave the blank lines of a print.
Short ridgeA ridge that begins, runs a short way and ends.
BifurcationOne ridge forking into two branches.
Ridge endingThe point where a ridge stops.
Dot (island)A ridge so short that it is only a spot.
How this list was compiled: Every name checked on 2026-09-30 in two independent places. (1) Federal Bureau of Investigation, The Science of Fingerprints: Classification and Uses (US government work, public domain), Project Gutenberg ebook 19022, https://www.gutenberg.org/ebooks/19022 (the three groups arch, loop and whorl; in plain arches the ridges enter on one side and flow out the other with a rise in the center; a loop’s ridges enter, recurve and end toward the side they entered from, and loops are about 65 percent of all prints, whorls about 30 percent; the two focal points, delta and core; the core is the approximate center of the impression, placed on the innermost recurve; the delta may be a bifurcation, an ending ridge, a dot or a short ridge in front of where the type lines diverge; a bifurcation is the forking of one line into two or more branches; ridges and furrows; ink adheres to the ridges). (2) Wikipedia, Fingerprint, https://en.wikipedia.org/wiki/Fingerprint (the three basic patterns arch, loop and whorl, about 5, 60 to 65 and 30 to 35 percent; ridge ending, bifurcation, short or independent ridge, island or dot, delta as a Y-shaped ridge meeting, core; friction ridges are raised portions of the epidermis; ridges and furrows). Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry. Invented prints, not any person’s; nothing is traced or copied. Licence: own work
How it works
The parts of a fingerprint are its pattern, which is an arch, a loop or a whorl, and the small details of its ridges. The second picture adds the core, the delta and four kinds of ridge detail.
Read the full guide
Tell the three patterns apart
Follow one ridge. In an arch it crosses from one side to the other with a rise in the middle. In a loop it comes in, turns back and leaves on the side it entered. In a whorl it circles the center.
Then look closely at the ridges
Ridges are the raised lines of skin, and furrows are the grooves between them. A ridge may fork, which is a bifurcation, or simply stop, which is a ridge ending. A short ridge runs only a little way, and a dot is shorter still.
A loop has one delta. A whorl has two, one on each side of its center.
Questions and answers
What are the three types of fingerprints?
Arch, loop and whorl. They are named for the path the ridges take: across with a rise in the middle, in and back out on the same side, or around a center.
Which fingerprint pattern is the most common?
The loop. The FBI’s fingerprint manual puts loops at about 65 percent of all prints and whorls at about 30 percent. Arches are the rarest, about 5 percent.
What is the core of a fingerprint?
The approximate center of the pattern. In a loop it sits on the innermost ridge that turns back.
What is a delta in a fingerprint?
The spot where ridges coming from three directions meet, often shaped like a Y or a small triangle. It is named after a river delta.