help me回答以下問題

Why are fingerprints used for identification?

Fingerprints offer an infallible means of personal identification. That is the essential explanation for their having supplanted other methods of establishing the identities of criminals reluctant to admit previous arrests.Other visible human characteristics change - fingerprints do not.
What are the methods for taking fingerprints?
Easiest and cheapest: rubbing pencil all over a small area of paper or index card to make an “ink” pad, pressing fingers onto the penciled area,lifting prints from fingers with transparent tape, and sticking tape to white index cards for reading.
High-tech, neat, and not too expensive: using purchased Identiprint materials.
How do we classify fingerprints?
Fingerprints can be classified by pattern types, by the size of those patterns, and by the position of the patterns on the finger.
Where on each finger do you see the most interesting patterns?
The interesting aspect is that many patterns that are similar to fingerprints can be found on the skin of many tropical fish.