Southern blotting is a technique used to detect specific DNA sequences. It involves extracting DNA from cells, cutting the DNA with restriction enzymes, separating fragments via electrophoresis, transferring DNA to a membrane, then adding a labeled probe to hybridize to complementary DNA sequences. The probe-hybridized DNA can then be detected through autoradiography. Southern blotting is used to identify DNA mutations and rearrangements and has applications in medical diagnosis and forensics.