A wire that connects the electronics of an electric guitar to the bridge. When the player touches the strings, he or she becomes a ground point for the circuit, which can greatly reduce buzz and hum problems. The downside is, since the guitarist’s body is in the circuit, if he or she touches a microphone or other piece of gear that is at a different polarity than the guitar/amp, there is danger of shock or electrocution. However, if everything is wired properly (test it before you put your mouth up to the microphone!), a string ground is perfectly safe.