DNA Fingerprinting

Southern hybridisation involves digestion, gel electrophoresis, blotting on a membrane, hybridisation with a labelled probe and autoradiography. PCR is not a step in it.

About 99.9% of the base sequence of DNA is the same in all humans; DNA fingerprinting looks at the regions that differ.
These regions are repetitive DNA, in which a small stretch of DNA is repeated many times; they form satellite peaks during density-gradient centrifugation and are called satellite DNA (mini-satellites and micro-satellites).
These sequences show a very high degree of polymorphism: the number of repeats (VNTR) differs from person to person and is inherited.
This polymorphism in satellite DNA is the basis of DNA fingerprinting.
The ratio of purines to pyrimidines is the same (1 : 1) in everyone, and the DNA of all tissues of a person (blood, skin, saliva) is identical, so these cannot be the basis.
Hence the basis is satellite DNA occurring as highly repeated short DNA segments.

DNA (genetic) fingerprinting identifies differences in repetitive DNA between individuals.
RFLP detects differences in the lengths of restriction fragments, and PCR amplifies very small DNA samples for this analysis.

Satellite DNA consists of short sequences repeated many times; it forms separate small peaks during density gradient centrifugation.
These sequences do not code for proteins but show a high degree of polymorphism: the number of repeats (VNTR) differs from person to person.
This polymorphism is the basis of DNA fingerprinting, developed by Alec Jeffreys.
DNA fingerprinting is used in forensic science to identify criminals from blood, hair, semen or skin, and to settle paternity disputes.
Hence satellite DNA is a useful tool in forensic science.

DNA fingerprinting (DNA profiling), developed by Alec Jeffreys, compares the DNA of individuals by studying highly variable regions called VNTRs (variable number tandem repeats) or satellite DNA.
The DNA is cut with restriction enzymes, the fragments are separated by electrophoresis, blotted, and hybridised with labelled VNTR probes (Southern blotting). The resulting band pattern is the DNA profile.
Each person (except identical twins) has a unique pattern, so it is used in forensics, paternity disputes and studies of populations.
It has nothing to do with the fingerprints on the fingers; the name only means that the pattern is as unique as a fingerprint.
So DNA fingerprinting refers to the molecular analysis of profiles of DNA samples.