File permissions explained. Why some files are locked and how to fix access

File permissions control who can read, edit, and run files. Every file has an owner who can change permissions. If you see 'access denied', you either don't own the file or its permissions are too restrictive.

Operating systems protect files using permissions. Each file has an owner and permissions that determine who can read it (view contents), write to it (edit/delete), and run it (run as a program). Permissions prevent accidental deletion of system files and help share files securely. When you see 'access denied', it means your user account doesn't have permission for what you're trying to do.