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:
“An actor must communicate his author’s given message—comedy, tragedy, serio- comedy; then comes his unique moment, as he is confronted by the looked-for, yet at times unexpected, reaction of the audience. This split second is his; he is in command of his medium; the effect vanishes into thin air; but that moment has a power all its own and, like power in any form, is stimulating and alluring.”
—Eleanor Robson Belmont (1878–1979)