XLR connector
The round, latching connector that carries nearly every microphone signal on a stage or in a studio.
The name comes from Cannon, whose X series gained a latch (L) and then a rubber insert (R) around the pins in the 1950s. Three pins is the audio standard: shield on 1, hot on 2, cold on 3. That order was only nailed down by AES14 in 1992, after decades in which American manufacturers happily wired hot to pin 3.
It is built to survive being stood on. The ground pin is longer than the others and mates first, so plugging in a live cable doesn't fire a thump through the PA. The same shell also carries digital audio over AES3 and, in its five-pin form, DMX lighting control.