Dark Mark

In the Harry Potter series created by J. K. Rowling, magic is depicted as a supernatural force that can be used to override the usual laws of nature. Many fictional magical creatures exist in the series, while ordinary creatures sometimes exhibit new magical properties in the novels' world. Objects, too, can be enhanced or imbued with magical property. The small percentage of humans who are able to perform magic are referred to as witches and wizards, in contrast to the non-magical muggles.

In humans, magic or the lack thereof is an inborn attribute. It is inherited, carried on "dominant resilient genes". Magic is the norm in the children of magical couples and less common in those of muggles. Exceptions exist: those unable to do magic who are born to magical parents are known as squibs, whereas a witch or wizard born to muggle parents is known as a muggle-born, or by the derogatory term "mudblood". While muggle-borns are quite common, squibs are extremely rare.

For a person's ability to perform magic to be of use, much training is needed. When "wild", typically with young and untrained children, magic will still manifest itself subconsciously in moments of strong apprehension, fear or anger. Magic can manifest itself on occasions of sadness as well. For example, Harry Potter once made his hair grow back after a bad haircut; set a boa constrictor on his cousin Dudley at the London Zoo; and, in anger, made Aunt Marge inflate to an enormous size. While this reaction is usually uncontrollable, Tom Marvolo Riddle, later known as Lord Voldemort, was able to "make things move without touching them...make animals do what he wanted without training them...make bad things happen to people who annoy [him]...or 'make them hurt if I [he] want[s] to'" when he was a young child, apparently intentionally. In addition, Lily Potter was able to guide and control the blooming of a flower by wanting to. Almost all magic is done with the use of a supporting tool or focus, typically a wand. On the subject of magic without the use of a wand, Rowling says:

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