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Is there any difference between a GUID and a UUID?

Whats the difference between a GUID and a UUID, and which should I use for true uniqueness?

Update: What things do I need for uniqueness too in the algorithm I choose?

1) MAC address of network card 
2) 128 bits (isn't 64 bits enough?) 
3) What if I have a multicore machine on the same MAC address. Isn't there a chance of duplicates?
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marked as duplicate by Nifle, Nick Dandoulakis, Otávio Décio, David Schmitt, Chris Lively Feb 17 '10 at 14:08


3 Answers

up vote 2 down vote accepted

A GUID is Microsofts implementation of a unique identifier (UUID).

A UUID is defined as


From Wikipedia.

If you need to create a new guid/uuid use my website:)


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Does your site create 64 bit or 128 bit GUIDs? –  Zubair Feb 17 '10 at 13:59
It uses Guid.NewGuid so thats 128 bit GUIDS! msdn.microsoft.com/en-us/library/system.guid.aspx –  Aim Kai Feb 17 '10 at 14:07
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Does this help: Stack OVerflow

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Yes thats great, thanks –  Zubair Feb 17 '10 at 13:57
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GUIDs are 128-bit UUIDs. You can use GUIDs and be sure of their uniqueness.

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