Within the books, technical details of magic are obscure.Of Harry's lessons, only those involving magical creatures, potions or divination are given in any detail.Spells are divided into rough categories, such as "charms", "curses", "hexes", or "jinxes".
Before publishing the first Harry Potter novel, Rowling spent five years establishing the limitations of magic—determining what it could and could not do.
"The most important thing to decide when you're creating a fantasy world," she said in 2000, "is what the characters CAN'T do." For instance, while it is possible to conjure things out of thin air, it is far more tricky to create something that fits an exact specification rather than a general one; moreover, any objects so conjured tend not to last.
However, Rowling has revealed that particularly talented wizards can cast spells without the aid of wand, although magic produced with one is generally more precise and powerful.
Spells can also be cast non-verbally, but with a magical wand.
She has described this as "a way of giving texture to the world".