PCR refers to the Polymerase Chain Reaction, which revolutionized the study of nucleic acids because it permitted very small amounts of DNA to be copied a bazillion times, giving you enough material to study and/or manipulate in various ways.
During the course of my career, I’ve had to become if not an expert, at least very familiar with the PCR process. This was not all that easy. Bear in mind, I started out as an inorganic chemist. Maybe that’s why this video cracks me up.