PCR is a common technique used to amplify specific regions of DNA. Put more simply, its a process that allows us to create copies of a piece of DNA. There are two main properties of PCR that we take advantage of - amplification (getting many copies) and isolation (of a single region).
I should note that the role of PCR has changed over time and I will mostly be focusing on the current use. Additionally, there are several variants based off the standard PCR, including rt/qPCR, but those will be covered in a different post.
Why do a PCR?
Typically PCR is just a step to let us do something else with a gene or region of DNA. It is the first step in gene cloning or for things like gene editing. It can also be used ‘genotype’ an individual for a gene, i.e. figure out which specific copy of a gene someone has.