why string instrument players shake their fingers while playing ?

Answer 1

Guess you don't really know anything about insturments do you? I'm only 10 & I've been playing for 3 years. They "shake" their fingers so they can do a sort of tecnique call vibrato. (vibration)

Answer 2

the shaking fingers thing creates what's called "vibrato"

its a neat sound that moves the pitch up and down just slightly, making the tune more interesting than if they just kept their fingers still

Answer 3

To create a vibrato . That is, a slight warble in the note that is very pleasing to the ear.