\m/ is the “devil horns” — the universal sign for rock and roll.
Two backslashes for fingers, the “m” for the middle and ring fingers pressed together, the slash for the thumb. Tilt your head. A hand. Two horns. You know it.
The gesture itself comes from Ronnie James Dio, the heavy metal singer who popularized it in the 1970s. He borrowed it from his Italian grandmother, who used it to ward off the evil eye. Dio turned it into a greeting, a battle cry, and a tribal marker. At concerts, thousands of people raise the horns in unison. It means: we are here, we are loud, and we belong to the same church.
Online, \m/ became shorthand for anything cool, intense, or metal. Someone shares a guitar solo? \m/. Someone survives a bad Monday? \m/. It is agreement, admiration, and solidarity in three characters. Variations exist: \mm/ for both hands, /\m/\ for extra enthusiasm, \m/(-_-)\m/ for the full body.
The symbol has leaked into mainstream culture. Your grandmother has probably seen someone do it on TV. But in metal communities, it still carries weight. It is not just a gesture. It is a password. When two strangers throw the horns at each other, they are acknowledging a shared history — of volume, rebellion, and volume.
Rock on.