VIOLIN: What is a SHOULDER REST and WHY IS IT IMPORTANT?

THIS IS THE TYPE OF SHOULDER REST WE ARE USING IN CLASS.

http://www.wwbw.com/Resonans-3-4-Violin-Shoulder-Rest-360417-i1129667.wwbw

THIS IS THE TYPE OF SHOULDER REST I USE (WOLF FORTE PRIMO). IT IS MORE EXPENSIVE BUT EACH SIDE CAN BE ADJUSTED FOR A BETTER FIT.

DO YOU NEED A SHOULDER REST?
CHECK THIS OUT TO LEARN MORE:

http://www.ehow.com/video_2375268_importance-shoulder-rest-violin.htm

http://www.ehow.com/video_2375269_the-shoulder-rest-violin.html?pid=1&cp=1

http://ezinearticles.com/?How-to-Choose-a-Violin-Shoulder-Rest&id=2191624

http://en.wikipedia.org/wiki/Shoulder_rest

http://www.stringsmagazine.com/issues/strings127/yourinstrument_127.htmlco.uk/violin_shoulder_rests.htm

http://simplyforstrings.com.au/blog/2009/04/20/the-right-rest-for-you/

http://www.wwbw.com/Wolf-Forte-Primo-Violin-Shoulder-Rest-464317-i1430821.wwbw

http://www.youtube.com/watch?v=92l-KjEJtIU

http://www.youtube.com/watch?v=lfZT3bW7G8A&NR=1&feature=fvwp