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

What is Interfaces in Laravel, and what role does it play in a real application? In Laravel, interfaces should be understood as part of a larger application architecture rather than as an isolated API call. Interfaces let application code depend on a contract while the container chooses a concrete implementation. 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: Laravel's service container resolves class dependencies and supports dependency injection, enabling services to depend on abstractions or collaborators without constructing them manually. The specific focus here is interfaces: Interfaces let application code depend on a contract while the container chooses a concrete implementation. 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.