A wish is a hope or desire for something. Fictionally, wishes can be used as plot devices. In folklore, opportunities for "making a wish" or for wishes to "come true" or "be granted" are themes that are sometimes used.
In Literature
offering wishes, illustration by John Bauer to Alfred Smedberg's The seven wishes]]In fiction a wish is a supernatural demand placed on the recipient's unlimited request. When it is the center of a tale, the wish is usually a template for a morality tale, "be careful what you wish for"; it can also be a small part of a tale, in which case it is often used as a plot device.The template for most fictional wishes is The Book of One Thousand and One Nights, specifically the tale of Aladdin, although in the tale of Aladdin the actual wishes were only part of the tale. Also, Aladdin's demands, while outrageous per se, were mainly variations on wealth (which is still often taken as the most 'common' request).Classically the wish provider is often a spirit,
Source:
http://en.wikipedia.org/wiki/Wish*