XLR connectors are the industry standard for professional microphones and audio equipment. The name comes from the Cannon X series connector with a Latch and Rubber boot — the X, L, and R of XLR. They have three pins: ground (Pin 1), positive signal (Pin 2), and negative signal (Pin 3).
The three-pin design enables balanced audio transmission. A balanced cable carries the audio signal in two versions — a positive and a phase-inverted negative. At the receiving end, the negative signal is flipped back and combined with the positive. Any interference picked up along the cable is common to both conductors and cancels out. This is why professional audio systems can run XLR cables hundreds of feet without picking up hum or noise.
For home studio use, the practical benefit is cleaner audio even with inexpensive cables. USB cables have no equivalent noise rejection — they rely on digital error correction, which has its own latency and quality limitations.
XLR microphones require an audio interface or mixer with XLR inputs. The interface converts the analog XLR signal to digital for your computer. Entry-level interfaces like the Focusrite Scarlett Solo provide one XLR input; the Scarlett 2i2 provides two.
XLR connectors lock in place with a latch mechanism, preventing accidental disconnection during live performance — a significant advantage over USB or 3.5mm connectors.