Ubuntu Enable & Setup Automatic Unattended Security Updates

Originally published at: https://www.cyberciti.biz/faq/ubuntu-enable-setup-automatic-unattended-security-updates/

I have minimal Ubuntu Linux 18.04 LTS server setup in the cloud. I read that one can configure Ubuntu Linux to download and install security updates when released automatically. How can I set up automatic security updates on Ubuntu Linux 18.04 or 16.04 LTS system?