Do you know the rules for Reincarnation?

I'm not sure what the rules are but I'd like to give my opinion. What I believe is that we all have a reason to be here on Earth, a purpose. So we are given one life to live and fulfill that purpose, that reason. But some of us fail to complete it so we are given another chance on Earth to live and try again. I don't really think anyone knows the rules of reincarnation because there is no solid evidence it can happen. We only hear stories and I don't think science will ever provide us with the evidence most of us seek. We just need to trust out faith and enjoy a little magic in this world obsessed with science.