[2] The mandolin has been a core instrument in bluegrass music from the beginning, along with guitar, fiddle, banjo, upright bass, and sometimes dobro.
The mandolin with its high toned strings, makes its contribution with a technique called a "chop," also known as chunking.
By releasing the pressure of the fingers shortly after striking each chord, the chops create a driving, percussive effect.
The melody instrument players, including the mandolinist, play simple harmonies, countermelodies or soft chopping in behind the singing, and take turns contributing bold improvisations and "licks" during the pauses and turnarounds.
A good mandolin break may stick fairly closely to the melody of the tune, or it may be almost all improvisation around the chord progression.
However, the mandolin's short, tight strings and "woody" tone have allowed its players to develop playing techniques which are unique to this instrument.
[1] In bluegrass music the tremolo notes are often short and intense, but can be gentle and sweet in the occasional slow-paced tune.
[1] Much of the bluesy feel of bluegrass instrumentals comes from the creative use of slide and hammer-on techniques and the use of notes from the blues scale.
Bluegrass mandolin players over time build up a repertoire of pre-practised passages called "licks" which can be inserted into breaks or turnarounds at appropriate moments during a performance.
Many bluegrass tunes are played at a rapid pace, and while a lot of improvisation goes on, including these "fancy bits" make the resulting music more impressive and exciting.