Basic shapes and patterns of fingerprints

The Arch pattern is made up of ridges lying one above the other in a general arching formation.

The tented arch pattern consists of at least one upthrusting ridge, which tends to bisect superior ridges at right angles, more or less.

The loop pattern consists of one or more free recurving ridges and one delta.

In order to distinguish between ulnar and radial loops you must:
1)  know from which hand the loop pattern comes from and;
2) place your hand palm side down over top of the impression and determine if the recurving ridges originate from the little finger side or the thumb side.

If the ridges flow in from the little finger side this would be an 'ulnar' loop.  If the ridges flow in from the thumb side this would be a 'radial' loop.
The whorl pattern consists of one or more free recurving ridges and two points of delta.  When the line of the fingerprint disc is placed on the two points of delta, it will bisect at least one of the ridges belonging to the core group.

In the twinned loop pattern, the recurving ridges present two loop formations, separate and apart.  There are two points of delta.  The flows for the deltas originate from the same side of the pattern.

The central pocket loop pattern consists of one or more free recurving ridges and two points of delta.  When the line of the fingerprint disc is placed on the two points of delta, it will fail to bisect any of the ridges belonging to the core group.

In the lateral pocket loop pattern, the recurving ridges present two loop formations, separate and apart. There are two points of delta.  The flows for the deltas originate from the same side of the pattern.
The composite pattern is composed of two or more different patterns, separate and apart exclusive of the arch.

The accidental pattern will contain two points of delta. One delta will be related to a recurve and the other will be related to an upthrust.