Domain hijacking is a type of internet attack where the attacker changes the domain name system (DNS) to redirect users to a fake website or prevent access to a legitimate website. It can happen through various methods, not just changing the DNS, as seen in the examples of Baidu and Diigo being hijacked in the past. Attackers can pretend to be the domain owner or registrar to modify registration information or transfer requests, and even sell the hijacked domains for profit. Another method is to modify the DNS records without authorization, resulting in DNS spoofing attacks. It is important for website owners to be aware of these risks and take preventive measures to secure their domains.