The palm mute, also known as palm muting, is a playing technique for the guitar. Palm mutes are executed by resting the edge of the picking hand's palm on the strings near the bridge, producing a dampened sound. The name is a slight misnomer, as muting is performed by the heel of the hand in general.

While seldom, if ever, encountered in classical music featuring the guitar, palm muting is now a standard technique among guitar players who play with a plectrum ("pick"). Palm muting is so widely used as to be idiomatic in hard rock, heavy metal, and particularly thrash or speed metal, but it is often found in any style of music that features electric guitars with distortion in the signal's pre-amplification stage. It is responsible for the stereotypical "chugging" sound of distorted guitar music.

Palm mutes in notation

In guitar tablature, palm mutes are rendered with a "P.M." or "PM", and a dashed or dotted line for the duration of the phrase to be muted. If the pitches of the muted notes are discernible, the fret numbers are given accordingly, otherwise they are represented with an X in lieu of a tab number. (If an X appears in lieu of a tab number but there is no P.M. directive, this usually means to mute the string using the fretting hand, not the picking hand.)

    P.M.------------|
e |------------------|
B |--8-------8-------|
G |--7-------7-------|
D |--6-------6-------|
A |--7-------7-------|
E |----0-0-0---0-0-0-|

Recorded examples of palm muting

One popular song with palm muting is "Basket Case" by Green Day, where power chords are accented then muted to create a sense of energy and urgency

    > PM--------| >  PM-| < PM--| >      PM-| < PM- > PM>  PM-| < PM--| <
e |-----------------|-------------------|-----------------|-------------------|
B |-----------------|-------------------|-----------------|-------------------|
G |-9---------------|-------------------|-----6-----6-----|-------------------|
D |-9-9-9-9-9-9-9-9-|-----9-------9-x-x-|-6-6-6-6-6-6---6-|-----6-------6-x-x-|
A |-7-7-7-7-7-7-7-9-|-9-9-9-9-9-9-9-x-x-|-4-4-4-4-4-4-6-6-|-6-6-6-6-6-6-6-x-x-|
E |---------------7-|-7-7-7-7-7-7-7-x-x-|-------------4-4-|-4-4-4-4-4-4-4-x-x-|

Palm muting can also be heard in The Animals' "House of the Rising Sun", and is employed on both acoustic and electric guitars by Al Di Meola. One example of the technique's use on acoustic guitar may be found in Di Meola's "Mediterranean Sundance".