I learned through a website and books as an adult...though I had learned to knit from my great grandmother when I was a child. I really think what book or website is helpful to you will depend on your way of learning. I would guess there are people out there who really need to have help from an experienced knitter too.
I have "how to knit" by Debbie Bliss...mainly because I liked the patterns in the book. I've found her descriptions of the actual process of knitting a little confusing, but knew enough to get through.
You could try starting with a kids book...."kids knitting" by Melanie Fallick is rather good...also shows you how to make your own knitting needles!
Oh, what I reminder...I need to finish the scarf I'm making for my mom!