MAC – Mandatory Access Control

is a security model to enforce restrictions on access to resources based on predefined rules and policies.

Access decisions are made by a system administrator or a security policy manager.
Uses labels or tags associated with subjects (users, processes) and objects (files, directories).
Labels and tags are used to define security levels or categories.
They are typically hierarchical, with different levels of importance or sensitivity.
Subjects can only access objects matching their level.
Even if a user has access to a resource above his level, he cannot access it.
Used in military and government environments, or similar.
Pros: High level data protection, granularity, avoids trojan horses, fewer errors
Cons: Scalability, Maintainability, Interferes with users work