UUIDs are widely used when systems need identifiers that are unlikely to collide. They are common in APIs, data records, test fixtures, and prototypes.
Why UUIDs are useful
They let you create unique-looking values quickly without setting up a database or counter. That makes them practical for local testing and demos.
Where they appear
You will often see UUIDs in REST APIs, event logs, object storage keys, and sample payloads.
Best practice
Generate only as many as you need for the current task so your sample data stays readable.