.ac

The .ac top-level domain is the Internet country code (ccTLD) for Saint Helena, Ascension and Tristan da Cunha, and primarily for Ascension Island. It is administered by NIC.AC, a subsidiary of the Internet Computer Bureau based in the United Kingdom.
Registration for the domain is open to anyone. The registry accepts registrations of internationalized domain names.
The domain is marketed by some domain-brokers as a domain for the city of Aachen, Germany, after the automotive license plate designation ("AC") for the city.
Use as an abbreviation for "academic".
Due to its similarity to the .ac ("academic") second-level domain that exists under some country code top-level domains, some educational institutions also register under the .ac top-level domain: