As the body of the violin is hollow it does make a good percussive instrument. Tapping the body in various ways has become popular with composers and using different parts of the hand can create different timboral effects. For example you can slap the body of the violin or tap with the pad of a finger. The composer should explain what is wanted by either writing in the notes at the front or in the score. The violin gives slightly different sounds depending on where it is being struck and also with the different parts of the hand. The option to dampen the strings is again there as striking the body of the violin will create the to resonate.
The violin can either be held like a cello when performing these techniques or as normal. Caution should be taken when striking the instrument, I would advise using a spare if you have one, also one of the techniques that can be used is to strike the violin with the fingernails. This will result in a short tapping sound but may cause varnish to chip off the violin causing damage.
It should also be noted that if one hand is used to perform the technique then it leaves the other hand free. For example if the violin was in the normal playing position and tapping with the right then it would leave the L.H. able to perform other techniques such as L.H. pizz such as in George Crumb’s Black Angels.