UUID
From ArchWiki
UUID stands for "Universally Unique IDentifier".
The intent of UUIDs is to enable distributed systems to uniquely identify information without significant central coordination. Thus, anyone can create a UUID and use it to identify something with reasonable confidence that the identifier will never be unintentionally used by anyone for anything else.
A UUID is a 16-byte (128-bit) number. The number of theoretically possible UUIDs is therefore 216*8 = 2128 = 25616 or about 3.4 × 1038. This means that 1 trillion UUIDs would have to be created every nanosecond for 10 billion years to exhaust the number of UUIDs.
In its canonical form, a UUID consists of 32 hexadecimal digits, displayed in 5 groups separated by hyphens, in the form 8-4-4-4-12 for a total of 32 characters. For example:
550e8400-e29b-41d4-a716-446655440000
Finding the UUID of a volume
Two possible ways to find the UUID of a volume:
# blkid
or
# ls -l /dev/disk/by-uuid
See also
Persistent block device naming