The Catalog Management system has two primary APIs: the DTO-based API and the object-based API, where the object-based API relies on the underlying Data Transfer Object (DTO) API.
## DTO object model
The DTO API is the core catalog API and primarily used directly in the catalog administration and indirectly through the Object API.
## Runtime object model
The runtime object model is primarily used during runtime. Entry is the main object that you will most likely work with.