Few technologies in the life sciences can claim to have been as pivotal as the polymerase chain reaction (PCR). PCR was developed in 1983 by Kary Mullis. The advent of the PCR thermal cycler and its release in 1987 automated the tedious task of manual temperature cycling, but it was the novel application of the heat stable Taq polymerase that really allowed PCR to flourish. Subsequent discoveries of additional thermostable polymerases and the mutation of other enzymes in the polymerase family has enabled the development of high fidelity, long read polymerases, all of which have added to the robustness of the PCR technique. PCR is constantly being modified, improved, and applied in new and interesting ways. This collection booklet explores the various ways PCR has been applied and changed over the years.