Why is domain name WHOIS lookup important?
A WHOIS lookup allows the website owner of a domain name to be retrieved. A whois lookup is a request on the database server of a domain registrar. These databases are usually publicly accessible. You can use the whois data in order to contact the website owner. The data is sometimes also used for legal purposes.
It is important for website owners to ensure that the information of their domain names in the whois records is up-to-date. This allows (potential) customers and others to easily contact the owner of the website or domain name.
There's also the possibility to register a domain name anonymously. In cases of private domain registration, the details of the domain name provider are listed in the whois information. There are also companies that specialize in anonymous domain registration. When a domain is registered privately, the domain name owner is less likely to receive spam email and it becomes more difficult to retrieve the owner's details.