What is a fingerprint?
Your fingerprint is made of lots of tiny ridges on the end of your finger. These ridges  form a pattern, a pattern that is unique for each person, even 'identical' twins!! You leave prints because your hand produces oil, and so when you touch something, a little bit of oil comes off, leaving a fingerprint.

Different types of fingerprints:
There are seven in total. They all fit into three categories: arches, whorls, and loops.
Here are pictures of all of them:
 
 

Here is a graph showing stats of the percentages of the different types of fingerprints:
Arches: 5%
Whorls: 35%
Loops: 60%
 

Fingerprints in identification:
Fingerprints are used a lot in identification as evidence. After a crime is commited, detectives search the crime scene for fingerprints. After they have found fingerprints, they log them into the computer, and then the computer finds 3 or 4 matches. But it's a person who specializes in fingerprints that finds the final match.

Finding fingerprints:
How do you find fingerprints? Detectives use three simple steps:
 1. find the fingerprint
 2. depending on which kind of surface the fingerprint is on, you dust the fingerprint with a different type of powder. The powder makes it visible.
 3. detectives use a piece of clear tape, and they put it on the fingerprint. When they remove it, they have another copy of the fingerprint, but in powder.

Movies vs. real life:
 

Movies:	Real life:
People are always caught with only fingerprints as evidence.	There is a very small chance that that will happen.
Guns always have fingerprints.	Guns are cleaned with oil, so there is a very small chance that fingerprints will get developed.
Fingerprints are always found.	There is only a 10% chance that this will happen.