Magic number (programming)

In computer programming, a magic number or file signature is a numeric literal in source code that has a special, particular meaning that is less than clear to the reader. Also in computing, but not limited to programming, the term is used for a number that identifies a particular concept but without additional knowledge its meaning is less than clear. For example, some file formats are identified by an embedded magic number in the file (see list of file signatures). Also, a number that is relatively uniquely associated with a particular concept, such as a universally unique identifier, might be classified as a magic number.