A UUID, or Universally Unique Identifier, is a 128-bit number used to uniquely identify information in computer systems. It is designed to be unique across different devices and networks, making it useful for various applications, such as databases and distributed systems. UUIDs are typically represented as a string of hexadecimal digits, divided into five groups. UUIDs can be generated in several ways, including using timestamps, random numbers, or specific algorithms. This versatility allows developers to create unique identifiers without needing a central authority, ensuring that each UUID remains distinct even when generated independently across different systems.