SELinux (read as S.E.Linux)

The main purpose of using SELinux is to protect the system from “unpredictable” security breaches.
It provides a kernel-level security protection based on a white-list policy and can protect from things like application bugs and application misconfigurations.
(Buggy/misconfigured FTP/HTTP/other daemons may give the users more privileges than they should)

When troubleshooting SELinux related permission issues, “ls -Z” is the command to view the “label”, which defines the access privileges.