What are some common hardening techniques for operating systems?

Common hardening techniques for operating systems include disabling unnecessary services and network ports, removing default user accounts and guest access, implementing secure password policies, enabling firewalls and antivirus software, applying regular security updates and patches, limiting administrative privileges, and configuring system auditing and logging. Additionally, hardening may involve deploying intrusion detection and prevention systems, implementing secure network configurations, and enforcing strict access controls based on the principle of least privilege.