What is a domain name registry? A registrar? A registrant?

A registry is an entity that maintains the master database of domain names for a particular top level domain (TLD). Afilias is the registry for the .INFO TLD.

The registry receives domain name information from registrars, who register domain names on behalf of registrants-people like you who would like to register and use a domain name. The registry puts that information into what is called a "zone file," which allows computers to route Internet traffic to and from domains around the world.