G#m7b5/B
What a random guitar chord! (You might be thinking that.)

The minor 7 flat 5 guitar chord is a good one to know.

You may be asking... " but when will I use this chord?" 

As I've  been making guitar teaching videos I've been redoing my chord videos as I go along and this chord happened to be in one of the videos I did in May. 

I realize that this may seem like "giving you a fish" instead of "teaching you to fish", but if you continue to study and understand about the basics of chord theory, then one day you will understand how these chords are made, and how you can use them in your playing in many songs, not just one song. 

Hal

https://youtu.be/pJrTcSbHrpk