Registrants (people like you) work with registrars (companies like Google Domains) who in turn work with registries (companies like Google Registry).
A registrar is an organization that manages the registration of domain names for one or more top-level domain (TLD) registries.
A registry is an organization that manages the administrative data for the TLD domains and subdomains under its authority, including the zone files that contain the addresses of the name servers for each domain.Registrant
A registrant is the registered name holder of a domain. A registrant holds the "rights" to the domain for the duration of the registration period.
Because a domain's registration can be renewed indefinitely (up to 10 years at a time), a registrant is often considered the "owner" of the domain.
A registrar is an organization that acts as an interface between a registrant (owner) and a registry. Registrars sell domain names, provide registration services, and offer other value-added services applicable to domains.
Google Domains is a registrar.
InterNIC maintains a directory of accredited registrars at www.internic.com/regist.html.
Registration is the process whereby a registrant registers a domain with a registrar. A registrant can register a domain for a period from 1 to 10 years. When the registration period expires, the registrant can renew or extend the registration. The registrant must provide contact information to the registrar for inclusion in the WHOIS database.
A registry is a database that contains registrant information for the second-level domains (google.com, example.com) beneath a given top-level domain (.com).
A registry operator is an organization that maintains the administrative data for one or more top-level or lower-level domains. For example, VeriSign is responsible for several top-level domains, including the .com, .net, and .name domains. A registry operator is given authority for a domain through ICANN.