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, like this: 123e4567-e89b-12d3-a456-426614174000. UUIDs can be generated in several ways, including using random numbers or based on timestamps and hardware addresses. Their uniqueness helps prevent conflicts when merging data from different sources, ensuring that each identifier remains distinct even when created independently.