I love to crochet things hats and blankets.   Once you learn how to use the crochet hook its easy 
I have heard that crocheting is all about hooks and knots if im right?
Yes.  Crocheting completes each stitch before continuing, while knitting lets you keep lots of stitches open 
That is really intereting I had no idea it was that involved
Oh yes.  There are lots of variations of knitting and crocheting.  Knitting has lots of consecutive rows of intermeshing loops
Can you use any kind of string?
Yarn is used to create the fabrics
I think my grandma used yarn when she would crochett.