The fundamental phases of assets starts with requirements or needs at the development stage and once the assets are developed, they are promoted to the QA stage for testing, after testing of the assets is complete, the assets are promoted to the production stage.

An asset's overall lifecycle can be split across two or more API Gateway instances. For example, assets that are in the development and test phases of their lifecycle can be maintained in one instance and assets that are deployed (that is, in production) can be maintained in a separate instance.

When the asset's lifecycle is split across multiple API Gateway instances, each participating instance is referred to as a stage. A stage definition in API Gateway describes an API Gateway instance by its name and configuration information.