Versioning is an important design topic for teams building REST APIs. Once an API is published, it may be used by mobile apps, web clients or third-party systems. Changes to the API can directly affect those clients.

Removing a field from the response, renaming a property, changing endpoint behavior or adding a required parameter can be considered a breaking change. Such changes may break existing integrations.

API versioning helps manage this problem. Adding v1 or v2 to the URL is a common approach. Header-based and querystring-based versioning are also possible. The right strategy depends on the architecture and the API consumers.

ASP.NET Core supports several versioning approaches through packages and routing conventions. The key is to provide a clear migration path and maintain backward compatibility where possible.

A good versioning strategy allows the API to evolve without breaking existing clients. This keeps the product flexible while protecting integrations.