Each fingerprint belongs to a classification based on the general shape of the pattern. Arches have fingerprints with ridges that start on one side and flow across and out the other side. They have no core and can have one delta. Loops have ridges that flow in and back out the same side, they have one core and one delta. Whorls can have completely circular ridges that don't flow out the end of the patterns at all, or they can have ridges that flow in and out of the same side on BOTH sides. Whorls always have 2 or more deltas.
There is a process to using fingerprints as evidence, and the crime museum offers a glimpse at the major stages of this process. After offering a little background on what a fingerprint is, this site summarizes the processes that follow a criminal investigation. The process steps include collecting, analyzing, comparing, evaluating, and verifying.
"The FBI's Criminal Justice Information Services Divisions provides a variety of services, information, and training involving fingerprints and other biometrics." This site provides a wealth of information relating to the biometrics division of the FBI. Here, you will find resources useful in training, forms for various security and identity checks, and several ongoing biometric initiatives supported by the FBI. This site contains links to many other resources useful in the above-mentioned areas. Law enforcement and forensic science personnel would most benefit from the information found here.