MS is a disease that attacks the myelin on nerves. I think it basically acts like an allergic reaction or something like that. Anyway, nerves get all wonky and don't work normally because their myelin (acts as like a protective coating) is depleted/gone. This leads to the symptoms of MS: the potential numbness, tingling, dizziness, etc. The effects vary from person to person, depending (I guess) on WHERE the MS attacks, and also from what type of MS they have. To the best of my knowledge, there are 4 kinds. The most common is Relapsing-Remitting. That basically means that the people with it have "flare-ups." It gets worse, and gets better. One day, they may feel okay, and the next--awful. Someone was allowed to put the link mssociety.com on one of my questions on this board, so I hope it's okay for me to put it also. This can help answer a lot of your questions. They also have a support thing there too. As for the deadliness of MS: it doesn't kill, however, it IS permanent; there's no known cure. But it won't kill. Let me know if you want to talk sometime. I'm usually around here at least once a day. My mom just got diagnosed a few months ago. Hope this helps you :D