When people are looking up websites or sending email, or most other online activities, they identify what servers they wish to connect to and what people to communicate with by means of domain names. These are alphanumeric names with sections separated by dots, like example.com or this.ca. The last section, such as .com or .ca, is called the Top Level Domain, or TLD, and in effect classifies the domain.

Each TLD is managed by a "registry" which keeps track of all domain names, regardless of which particular registrar was used to register them. They maintain a central list so that the same name cannot be registered by different registrars, allowing names to reliably point to the same servers.

The .ca TLD is what is refered to as a "country code TLD" or ccTLD. These are domains based on the standard 2 letter abbreviation for a country's name, and are initially reserved for that country. While some TLDs, like the .tm and .tv domains have been predominantly used by those outside the country, others like .ca have been designed to serve the country they represent specifically.

While the .ca domain is for all of Canada, CIRA has created a second level of the domain relating to the provinces or territories. These are referred to as "province level" domain names, and use the 2 letter province/territory abbreviation before the .ca to indicate the province level. Province level domains available are: