system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we use XLR input for microphones instead of a 6.3mm jack like we do with guitars?
gpt
XLR (which, technically is only a connector standard) provides a *balanced* signal path.   Balanced lines allow better signal quality because they are less susceptible to interference.  Microphones tend to have much longer cables than guitars and so tend to be more affected by noise/interference.   XLR also allows "phantom power", which allows you to send power to microphones that require it.    Why not guitars?  Guitars (almost always) have high-impedance , high-output pickups and neither of these make a balanced line reasonable. And short cable runs.  Mics also plug into a board, where as you plug your guitar into an amp...so you'd need XLR inputs there, too.

Final point:  You can run balanced lines on XLR or 1/4" (6.3mm) but the connectors for 1/4" are 3 conductor, not 2.