Muting

There are a few kinds of muting. The most common is to allow the heel of your picking hand to gently rest on the strings near the bridge so that you can still hear the note, but not the ringing. This gives the guitar a more percussive sound. Rhythm player often use this technique to make their part more compact sound wise, a funkier sound than ringing chords.

Lead players often mute strings that are not being played so that they can really attack the ones that are being played without unwanted notes being struck by mistake. If they are struck, they choke off instantly.

Slide player, like myself, must also mute unwanted strings so that notes generated by the friction of slide don't ring out and ruin the music. I use the tips of my picking fingers to mute any unplayed strings.