Universally Unique Identifers (UUID) are a standardized unique indentifier in the form of a 128 bit number. In it's canonical form UUIDs are represented by a 32 digit hexadecimal number in the form of xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
UUIDs are used in column comparison in Cassandra.
The LexicalUUIDType is used for a non-time based comparison. It is compared lexically, by byte value.
The TimeUUIDType is used for a time based comparison. It uses a version 1 UUID.