This is the Internet country code top-level domain (ccTLD) for Norway.
Norid is the domain name registry.
The .NO domains are for Companies and/or Individuals that reside in Norway.
The requirements are the following:
For Companies: Must be registered in the Norwegian Business Register (Brønnøysund Register Centre). Provide exact name of company, contact person, address and phone in Norway.
For Individuals: Must be registered in the National Registry (Folkeregisteret) and have a Norwegian post address. Follow the instructions here: http://pid.norid.no to get the PID number used for registration.
Important: the maximum number of .NO domain names per organization is limited to 100 and per individuals is 5.