The clean-core strategy is fundamental to ensuring that the Digital Core remains stable and reliable during operations and future upgrades. By following this strategy, any extensions made are guaranteed not to affect the core system upgrades, and likewise, system upgrades will not disrupt the functionality of the extensions. This is achieved by using well-defined and stable interfaces for extensions to interact with SAP business objects, ensuring compatibility and stability across system updates.
Reference = The SAP architecture guidelines which prescribe maintaining a clean core, detailing how to develop extensions that are compatible with SAP's upgrade strategy and protect the integrity of the core system.