What is Polymorphic relations in Laravel, and what role does it play in a real application?

What is Polymorphic relations in Laravel, and what role does it play in a real application? In Laravel, polymorphic relations should be understood as part of a larger application architecture rather than as an isolated API call. Polymorphic relations allow one related model to belong to more than one model type through a type-and-ID pair. A strong understanding includes its purpose, the layer where it belongs, the data or request flow it affects, and the situations where another mechanism may be more appropriate. Practical context: Eloquent relationships describe how models connect so application code can access related data using expressive methods instead of hand-building join logic for every use. The specific focus here is polymorphic relations: Polymorphic relations allow one related model to belong to more than one model type through a type-and-ID pair. This question is designed to test not only terminology, but also how the concept fits into Laravel's request, application, database, security, or deployment workflow.