The Internet is a global system of inter-connected computer networks that use the standardized Internet Protocol Suite (TCP/IP). It is a network of networks that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by copper wires, fiber-optic cables, wireless connections, and other technologies.
This is the company that manages your domain name (e.g. www.companyname.com). A domain name registrar is a an organization or commercial entity, accredited by the Internet Corporation for Assigned Names and Numbers (ICANN) or by a national country code top-level domain (ccTLD) authority, to manage the reservation of Internet domain names in accordance with the guidelines of the designated domain name registries and offer such services to the public.
A web hosting company is a type of Internet hosting service that allows individuals and organizations to make their website accessible via the World Wide Web. Web hosts are companies that provide space on a server they own or lease for use by their clients as well as providing Internet connectivity, typically in a data center. Web hosts can also provide data center space and connectivity to the Internet for servers they do not own to be located in their data center, called co-location. This is the company that keeps all your website files on one of their servers.
A company like Web Candy, who designs and creats the files needed to create your website. It should be the web designers responsibility to ensure that the files that make up your site get properly transferred onto the server.