A globally unique identifier (GUID, /ˈɡwɪd/ or /ˈɡuːɪd/) is a unique reference number used as an identifier in computer software. The term GUID typically refers to various implementations of the Universally unique identifier (UUID) standard.
GUIDs are usually stored as 128-bit values, and are commonly displayed as 32 hexadecimal digits with groups separated by hyphens, such as 21EC2020-3AEA-1069-A2DD-08002B30309D. GUIDs generated from random numbers contain 6 fixed bits saying they are random and 122 random bits, the total number of unique such GUIDs is 2122 or 5.3×1036. This number is so large that the probability of the same number being generated randomly twice is negligible; however other GUID versions have different uniqueness properties and probabilities, ranging from guaranteed uniqueness to likely non-uniqueness.
Read more about Globally Unique Identifier: Common Uses, Binary Encoding, Text Encoding, Algorithm, Non-unique GUIDs, Sequential Algorithms, Uses, Subtypes, XML Syndication Formats
Famous quotes containing the word unique:
“Most women of [the WW II] generation have but one image of good motherhood—the one their mothers embodied. . . . Anything done “for the sake of the children” justified, even ennobled the mother’s role. Motherhood was tantamount to martyrdom during that unique era when children were gods. Those who appeared to put their own needs first were castigated and shunned—the ultimate damnation for a gender trained to be wholly dependent on the acceptance and praise of others.”
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