Do you know UUID class in java?

Problem statement:
What do you mean by UUID class in java?
UUID [Universally Unique Identifier]
A class that represents an immutable universally unique identifier (UUID). A UUID represents a 128-bit value.
Ex - 

 0xFFFFFFFF00000000 time_low
 0x00000000FFFF0000 time_mid
 0x000000000000F000 version
 0x0000000000000FFF time_hi