A DNA primer, made up of a random sequence of bases, used with the polymerase chain reaction (PCR) to amplify segments of an organism’s DNA. The primer effectively ‘selects’ all regions of DNA that happen to lie within inverted copies of the primer sequence. These regions, which will vary in length, are thus amplified by PCR and produce a series of bands when separated by electrophoresis. Because of variation in the sites of the primer sequences among individuals, the pattern of bands represents a genetic ‘fingerprint’ unique to each individual. This makes RAPD (pronounced ‘rapid’) PCR a useful technique for taxonomic studies, assessing kinship, or forensic investigation.