The following is a list of the most common second-level domains.

The following second-level domains are in use with their official descriptions.

Second-level domains on were also commonly used by individuals, although and are now alternatives.

However, there are some second-level domains that has more rules when registering.

Instead, registrations are made under a selection of second-level domains.

The second-level domain was permitted from June 2011, which gave individuals the possibility to register.

It is not possible to register a new second-level domain in .

Some second-level domain names are no longer actively used.

While any party with a Japanese mailing address can get a second-level domain (example.

Other second-level domains exist for organizations of certain types, such as municipalities and schools.

The other second-level domains are managed by various government agencies, and generally more strongly controlled.

Second-level domains are not available to the public.

There are two private second-level domains that exist for historical reasons, .

Second-level domain registrations at the time were (by modern standards) relatively expensive.

Network Information Centre and second-level domains must be used.

Users are asked to not register with a geographic second-level domain unless they have a local presence in the area.

In contrast, paid web hosts will usually provide a second-level domain along with the hosting (www.yourname.com).

Any individual may register for second-level domain names.

Third-level domains have restrictions based on which second-level domain they are registered under.

There are some second-level domains in use, however these are not required:

As an example, in the domain example.co.uk, co is the second-level domain.

With the new policies, Colombia would be able to sell second-level domain names to the world, such as widgets.

Second-level domains that have active registrations are listed below.

Registration of other second-level domain names directly under .

Italicised entries are legacy second-level domains that refer to individual organisations.