During the registration of your domain, certain information is submitted to the WHOIS database according to the requirements of the registration authority.
WHOIS information includes the contact details for the domain as well as the assigned IP address, name servers, registration term, etc. The respective registry or ICANN is responsible for the publication of your domain information.
You can find out who owns or manages a domain by performing a WHOIS lookup. This can be useful for contacting a domain owner about technical problems with the website or in case of violation of third party rights. In addition, a WHOIS lookup will help you find the owner of a domain you may want to buy.