2002 Honda Civic knocking sound when I turn

2002 Honda Civic mileage: 46,000. When I make turns in my car I hear a knocking sound? I was told that it is due to worn CV Boots. I was under the impression that the boot just held the oil and protected the joint or something from dirt. I thought that I would need to replace my CV joints which would be much more expensive. Would getting two new CV boots help fix the knocking on my car? And is there anything I can do to prevent this from happening again? Thanks for your help.