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

What is Upload security in Laravel, and what role does it play in a real application? In Laravel, upload security should be understood as part of a larger application architecture rather than as an isolated API call. File validation, storage isolation and least-privilege access are important because uploaded content can be attacker-controlled. 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 handles uploaded files through the request object and storage APIs, with validation used to control size, type and other constraints. The specific focus here is upload security: File validation, storage isolation and least-privilege access are important because uploaded content can be attacker-controlled. 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.