A domain name represents your "address" on the Internet. It is a written phrase that contains several components separated by a period ("dot").
Internet computers that track and locate each domain name actually use numeric addresses (e.g. 188.8.131.52) , so that within the system each domain name has a numeric equivalent. You don't have to worry about this since Domain Name Servers (DNS) take care of the matching. However, this is the reason why each domain must be assigned to a functioning Domain Name Servers