A universally unique identifier (UUID) is, in short, what it says it is: a string of letters and numbers intended to uniquely identify information. Within the context of identity and access management at Harvard, UUIDs are used as an internal identifier for users and, in the future, other non-person resources. We will gradually be migrating to the use of the Harvard UUID (also known as "HarvardKey"), rather than the HUID, across the board for identity and login control.
What About HUIDs?
Because not everyone at Harvard who needs access to resources is eligible to be issued a HUID number or ID card, we need to base identity and access controls on an identifier available to every Harvard affiliate. In addition, as more and more non-person resources such as microscopes and other research equipment are added to Harvard's "Internet of things," identification and provisioning via HUID becomes less and less viable. Furthermore, UUIDs can be created by multiple organizations within Harvard without the need for coordination — yet another reason why the implementation of UUIDs has been specified by Harvard's CIO Council.
Specifics on Harvard's Use of UUIDs
The specification also designates how bits are output into a string format consisting of letters and numbers in the set "a-f" and "0-9", respectively, along with hyphens as separators. The letters are not case-sensitive, and some systems will output the string for with letters in uppercase and some in lowercase. Here's an example UUID in string format (created via the "uuidgen" in bash on a Mac): CF12F521-D158-4C3F-A930-902FE50F922F
Some systems store the string format instead of the bits.
Source: Marlena Erdos