I was taught that magic is the changing of one or more things into something entirely different. When I asked my witch teacher to give me an example, she said:-
"Take an amount of flour. Some water, some yeast,a little sugar, a little salt, a little oil. Mix them together. Would you eat that soggy mess? But if you apply heat to that mixture, a strange thing happens. It changes into something entirely different. It becomes bread! That's magic!"