The polymerase chain reaction (PCR) has revolutionized forensic science, particularly in DNA profiling. PCR was introduced to forensic science in the 1980s, marking the beginning of a new era in DNA analysis. This review examines the evolution of PCR from its inception to its current applications in forensic science, focusing on the driving factors behind its evolution and the challenges of profiling inhibited and degraded samples. The review also discusses the development of newer PCR methods and their potential future directions. Key aspects covered include: 1. **General Principles of PCR**: PCR amplifies specific regions of DNA through an enzymatic reaction involving dNTPs, thermostable DNA polymerase, template DNA, primers, and a buffer. 2. **Historical Significance and Applications**: PCR's role in DNA fingerprinting and the identification of human remains is highlighted, with notable cases such as the identification of the Romanov family. 3. **Driving Factors of PCR Evolution**: The need for standardization, reliability, and reproducibility in forensic DNA analysis led to the formation of organizations like EDNAP, ENFSI, and SWGDA. 4. **Current PCR Workflows**: Traditional PCR, quantitative PCR (qPCR), and Rapid PCR are discussed, with a focus on their applications and differences. 5. **Fundamental Factors of PCR**: The importance of primer melting temperature and DNA polymerase processivity in PCR cycling conditions is emphasized. 6. **Evolution of PCR Cycling Conditions**: The evolution of PCR cycling conditions for STR profiling, mtDNA testing, and SNP analysis is reviewed, highlighting the challenges and advancements. 7. **Recent Developments in PCR**: Advances in PCR technology, including increased speed, sensitivity, and discrimination power, are discussed. 8. **Optimization of Commercially Available Kits**: Improvements in PCR buffers, DNA polymerases, and primers have enhanced the ability to generate DNA profiles from trace materials. 9. **PCR Amplification Kinetics**: The insights gained from fully quantitative PCR (qPCR) into the kinetics of PCR amplification are highlighted. 10. **Recent Developments Beyond Forensics**: The integration of PCR with Lab-on-a-Chip devices and intelligent computer systems is discussed, emphasizing real-time monitoring and optimization. The review concludes by addressing remaining challenges in PCR for DNA profiling, particularly the requirement for large quantities of good-quality genetic material.The polymerase chain reaction (PCR) has revolutionized forensic science, particularly in DNA profiling. PCR was introduced to forensic science in the 1980s, marking the beginning of a new era in DNA analysis. This review examines the evolution of PCR from its inception to its current applications in forensic science, focusing on the driving factors behind its evolution and the challenges of profiling inhibited and degraded samples. The review also discusses the development of newer PCR methods and their potential future directions. Key aspects covered include: 1. **General Principles of PCR**: PCR amplifies specific regions of DNA through an enzymatic reaction involving dNTPs, thermostable DNA polymerase, template DNA, primers, and a buffer. 2. **Historical Significance and Applications**: PCR's role in DNA fingerprinting and the identification of human remains is highlighted, with notable cases such as the identification of the Romanov family. 3. **Driving Factors of PCR Evolution**: The need for standardization, reliability, and reproducibility in forensic DNA analysis led to the formation of organizations like EDNAP, ENFSI, and SWGDA. 4. **Current PCR Workflows**: Traditional PCR, quantitative PCR (qPCR), and Rapid PCR are discussed, with a focus on their applications and differences. 5. **Fundamental Factors of PCR**: The importance of primer melting temperature and DNA polymerase processivity in PCR cycling conditions is emphasized. 6. **Evolution of PCR Cycling Conditions**: The evolution of PCR cycling conditions for STR profiling, mtDNA testing, and SNP analysis is reviewed, highlighting the challenges and advancements. 7. **Recent Developments in PCR**: Advances in PCR technology, including increased speed, sensitivity, and discrimination power, are discussed. 8. **Optimization of Commercially Available Kits**: Improvements in PCR buffers, DNA polymerases, and primers have enhanced the ability to generate DNA profiles from trace materials. 9. **PCR Amplification Kinetics**: The insights gained from fully quantitative PCR (qPCR) into the kinetics of PCR amplification are highlighted. 10. **Recent Developments Beyond Forensics**: The integration of PCR with Lab-on-a-Chip devices and intelligent computer systems is discussed, emphasizing real-time monitoring and optimization. The review concludes by addressing remaining challenges in PCR for DNA profiling, particularly the requirement for large quantities of good-quality genetic material.