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

What is Thin controllers in Laravel, and what role does it play in a real application? In Laravel, thin controllers should be understood as part of a larger application architecture rather than as an isolated API call. Moving complex business logic into services or domain classes can keep controller methods easier to read and test. 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: Controllers group related request-handling logic and commonly coordinate validation, services, models, redirects, views and API responses. The specific focus here is thin controllers: Moving complex business logic into services or domain classes can keep controller methods easier to read and test. 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.