This document provides an overview of SELinux, including its introduction, access control mechanisms, policy, administration, and benefits. SELinux is a Linux security module that implements mandatory access controls to confine processes and restrict their access. It defines types for objects like files and directories, domains for processes, and roles to determine what access users and processes have. SELinux policy enforces these controls and can be configured through booleans and modified policy modules. It helps strengthen security by auditing access and confining services like web servers even if they are compromised by an attack.