.ca is the Internet country code top-level domain (ccTLD) for Canada. The domain name registry that operates it is the Canadian Internet Registration Authority (CIRA).
Registrants can register domains at the second level (e.g., example.ca). Third-level registrations in one of the geographic third-level domains defined by the registry (e.g. example.ab.ca) were discontinued on October 12, 2010, but existing third-level domain names continue to be supported.