DNSSEC (Domain Name System Security Extensions) is a security protocol that allows the verification of the authenticity and integrity of data in the Domain Name System (DNS) of the internet, by using public key cryptography. It provides additional security features to prevent DNS spoofing and cache poisoning. DNSSEC digitally signs DNS records to ensure that users are communicating with the correct servers and that the data being shared has not been tampered with during transmission. This helps to prevent cyber attacks such as phishing, man-in-the-middle attacks, and DNS hijacking.