What does XLR stand for and why are XLR cables important to microphones? XLR connectors were originally patented by Cannon as part of their X series cables/connectors. XLR proved to be the best of the series. Cannon no longer has the patent, but professional mics nearly all have XLR outputs and XLR cables carry their balanced audio signals from mic output to preamp.
For a detailed read on microphones and XLR, check out my article Why Do Microphones Use XLR Cables?
What is an XY microphone pair? An XY pair is a coincident pair stereo miking technique. An XY pair has two cardioid microphones (typically top-address pencil mics) positioned with their capsules together but pointing 90° to 120° from one another.