There are two main types, known as ridge endings and bifurcations. Sometimes, other details; such as, the points at which scars begin or terminate, are considered minutiae.

The number and locations of the minutiae vary from finger to finger in any particular person, and from person to person for any particular finger; for example, the thumb on the left hand.

When a set of finger images is obtained from an individual, the number of minutiae is recorded for each finger. The precise locations of the minutiae are also recorded, in the form of numerical coordinates, for each finger.

The result is a function that can be entered and stored in a computer database. A computer can rapidly compare this function with that of anyone else in the world whose finger image has been scanned.