The PCR technique is a vital tool in many areas of life sciences. PCR is a method for the amplification of DNA that has revolutionised molecular biology and has many and varied applications in many and diverse areas of biological and clinical science. The PCR techniques in use today are almost exclusively based on real-time PCR, or quantitative PCR (qPCR) technology. Current real-time PCR technology has applications in a huge range of scientific areas. We provide here a review of PCR technology for competent and advanced users. Most of the information provided on these pages is from published books and papers written by leading scientists. The review includes PCR protocols, procedures and techniques, PCR troubleshooting, a description of PCR machines, tips and advice on primer design, PCR applications and much more. Also provided is a full review of PCR theory, both traditional, legacy PCR and real-time quantitative PCR or qPCR.