UUID

A UUID, or Universally Unique Identifier, is a 128-bit value written as 32 hexadecimal digits in five hyphen-separated groups. Its purpose is to let independent systems generate identifiers that will not collide without coordinating with each other. The most common form, version 4, is almost entirely random, and the space of possible values is so large that duplicates are effectively impossible in practice. UUIDs are ideal as database keys, request identifiers, and file names where uniqueness matters more than readability. They are not secret or unguessable by design, so a version-4 UUID should not be treated as a security token on its own.