WHOIS (literally: “Who is it”) is a publicly available network protocol and service that is used to request and obtain registration information regarding the ownership or administrative contact of a given domain name or IP address. This protocol is a fundamental element in the management of Internet resources and provides a mechanism for transparency and accountability in the digital space.
Conceptually, WHOIS serves as an identification database. The information provided through this protocol (including the name, address, telephone and email of the registrant) is vital for administrative, technical and legal purposes. In the SEO context, albeit indirectly, the completeness and publicity of WHOIS data can be viewed by search engines as a weak signal of legitimacy and trustworthiness of a given website.
It is important to note that due to regulations such as GDPR, access to full personal data in WHOIS is severely limited for many domains, with some of the information being hidden or replaced with registrar data (the so-called Private Registration). However, the protocol remains the main mechanism for tracking the ownership of Internet resources.