Whois is a protocol that is access to registering information. You can reach when the website was registered, when it will be expire, what is contact details of the site with the following informations.
In a nutshell, it includes these informations;
% This is the RIPE Database query service.
% The objects are in RPSL format.
% The RIPE Database is subject to Terms and Conditions.
% See http://www.ripe.net/db/support/db-terms-conditions.pdf
%ERROR:201: access denied for 2600:3c03:0:0:f03c:91ff:fe70:15f
% Sorry, access from your host has been permanently
% denied because of a repeated excessive querying.
% For more information, see
% This query was served by the RIPE Database Query Service version 1.94.1 (HEREFORD)