Globally Unique Identifier

What Does Globally Unique Identifier Mean?

A globally unique identifier (GUID) is a 128-bit number created by the Windows operating system or another Windows application to uniquely identify specific components, hardware, software, files, user accounts, database entries and other items.


GUIDs are part of the universally unique ID (UUID) standard that is used in Windows and Windows applications.

Techopedia Explains Globally Unique Identifier

GUIDs were initially developed to keep track of instances of Component Object Model (COM) objects and are still used to identify COM DLLs in the Windows registry.

GUIDs were created with an algorithm that employed the user’s media access control (MAC) address. This system was later dropped because users were concerned that documents could be traced back to individual machines. GUIDs can now be created in a number of different ways using a combination of unique settings.


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Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…