# Changes

Where changes to the API come from, what a breaking change is, and how you compare the specification against your version, without promising anything that does not exist.

> **Type:** area
> **For:** Anyone who operates an integration and wants to know when and how the API changes and how to recognize a breaking change.

## Keep track

| Page | When you need it |
|---|---|
| [Stability classes and sunset](/changes/stability-and-sunset) | What stable, beta, and internal promise, how long the period between announcement and shutdown is, and how your client recognizes a sunset on its own. |
| [Release trains, notes, and deprecations](/changes/release-notes) | How a release train comes about, how its notes are structured, what is attached to the release, and what applies to deprecations today. |
| [Packages and their versions](/changes/packages) | Which version of the API client, Apps SDK, CLI, and contracts applies and what changed for developers in each version. |
| [Compare the specification against your version](/changes/compare-specification) | Save openapi.json with a date, reload it with every train, and compare paths, required fields, and error codes, with the site and your own environment side by side. |