Magic

Recently i finished reading another very interesting book " Brida". Its main theme revolved around magic...the story of 21 year old Brida who wants to learn about magic. the book talks about the tradition of the moon and the sun. It describes the rituals which one has to undergo to be initiated into the world of magic thereby treading the path between the visible and the invisible. Magic in this sense is then portrayed as the bridge within the visible and invisible. What really concerned or rather bothered me after i finished reading this book was that does magic actually exist or existed? Is it a form of specialised knowledge which can be learnt through an elaborate procedure or ritual? I have often heard of terms such as Black magic but does it actually exist? What are the different forms of magic? How can we learn them? There are many questions but few answers and they seem to be hidden for now.