Test learners' understanding of PCR fundamentals and the common limitations that impact clinical diagnostic accuracy. Scope includes molecular mechanism (thermal cycling, polymerase activity), assay types (conventional PCR, RT-PCR, real-time/qPCR), analytical performance (sensitivity, specificity, limit of detection, dynamic range), and practical constraints (sample quality, inhibitors, contamination, primer/probe design, multiplexing) plus QC and mitigation strategies to reduce false results.