Dissociative Identity Disorder (Multiple Personality Disorder)

I read the article, Dissociative Identity Disorder (Multiple Personality Disorder) on webMD.com. In this article it explains exactly what Multiple Personlity Disorder really is and what might cause it. Many beileve that it is an illness that is caused from repetitive physical or sexual abuse as a child. It is believed to be a copping excercise to block out the pain or somewhere the person does not wish to be. During this, the person will switch into the other "alter" known as the the "switching" period. "Switching" may take minutes, hours , or even days. The "alter" may have its own sex, race, age, posture, and even dialect, the "alter" may even be an animal. Overall Multiple Personality Disorder is a copping excercise that involves another personality practically living inside you, switching on when the person wishes to block someting out.Although i understand the basic idea of this illness I'm still not sure as to how it really takes play. I don't fully grasp how an entire new personality can just happen, how when someone wants to block out the pain there alter ego takes play. Where does the real person go? Where does this other personality come from? Does the real person know that someone is taking over their body, did they plan for the alter ego to kick in? I have so many questions it's just so hard to understand. I would like to meet someone who has this illness, but would they know they had it? All in all this illness it just way to complicated to grasp in one day and I'm hoping by reading the book Dr.Jekyll and Mr.Hyde I will learn a little bit more about this overwhelming illness.