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

What is Security boundary in Laravel, and what role does it play in a real application? In Laravel, security boundary should be understood as part of a larger application architecture rather than as an isolated API call. Mass assignment protection reduces the risk of a request setting attributes such as role, status or ownership fields accidentally. 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: Mass assignment controls which attributes may be assigned through methods such as create and fill, helping prevent unintended fields from being populated from request data. The specific focus here is security boundary: Mass assignment protection reduces the risk of a request setting attributes such as role, status or ownership fields accidentally. 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.