550e8400e29b41d4a716446655440000

550e8400e29b41d4a716446655440000 is a 128-bit value that is widely used as a canonical example of a UUID in documentation and software development. When written with hyphens, the commonly cited form is 550e8400-e29b-41d4-a716-446655440000.

In the context of UUIDs, this string represents a universally unique identifier created to be globally distinct without a central coordinating authority. UUIDs are used to identify information in distributed systems, databases, files, and other resources, ensuring that identifiers remain unique across space and time.

The format shown by this example follows the standard UUID representation: 32 hexadecimal digits grouped as 8-4-4-4-12, with hyphens separating the groups. In this particular UUID, the third group begins with the digit 4, indicating that it is a version 4 UUID, which is generated from random or pseudo-random numbers. The first digit of the fourth group is a, which corresponds to the RFC 4122 variant and signals the specific layout used for UUIDs in that specification.

Because the digits are effectively random, the likelihood of a collision is extremely small, making such identifiers practical for use in large-scale and distributed applications. The example 550e8400e29b41d4a716446655440000 is not tied to any real-world object; it is intended as a reference value to illustrate the structure and generation of UUIDs.

See also: UUID, RFC 4122, version 4 UUID.