Two fingerprints are matched not by their overall swirl but by the small events along the ridges — the points where ridges start, stop and split. These features are called minutiae (sometimes "Galton points", after Francis Galton), and their arrangement is what makes a finger identifiable.
The main types
The features examiners look for include:
- ridge ending — where a ridge simply stops,
- bifurcation — where one ridge splits into two,
- dot (island) — a very short ridge,
- enclosure (lake) — a ridge that splits and rejoins,
- plus spurs, bridges and crossovers.
This is level 2 detail — the workhorse of fingerprint comparison, sitting between the overall pattern (level 1) and the fine pore-and-edge detail (level 3).
It's the arrangement that counts
What individualises a finger is not any single minutia but the overall configuration — the types of features, their positions relative to each other, and the number of ridges between them. Automated systems (AFIS) encode exactly this map of minutiae to search databases.
Is there a magic number?
People often ask how many matching minutiae "prove" identity. Historically some jurisdictions used fixed thresholds — the UK once required 16 points — but England and Wales abandoned the numeric standard in 2001 in favour of a holistic assessment of the quality and quantity of agreement. Most of the world takes this holistic view: it's the strength of the correspondence, not a point count, that matters.