Is popping your knuckles bad?

I'm a high school student and I have to do a paper on popping knuckles. I need to know every little detail you could possibly think of. Such as, why do people crack their knuckles, is it bad for you, why is it bad, what could happen if you did it throughout your entire life? Anything and everything. And please if you don't mind I have to do an interview with an expert, meaning email or over the internet. please let me know if you can help me at all. I've been searching but I still need more information. Also, with every bit of information I'm supposed to have a MLA citation from every website I use. so please post your sources. If you would like to help me with the interview my email is craziikidd@rocketmail.com thank you so much.