Identifier Design

Once an API exposes an identifier, that value can become a lasting reference. Customers save order IDs, partners store book references, and support agents copy shipment IDs into tickets. Those values may outlive the database layout, the resource's display name, and the service that originally created them.

Identifier design determines whether those references remain useful.

This chapter explains identity scope, stability, generation choices, public and internal identifiers, and the rules clients need for storing and submitting IDs. The examples use a fictional bookstore API.