|TLD type||Country code top-level domain|
|Registry||Ascension Island Network Information Centre (run by Internet Computer Bureau)|
|Sponsor||Cable and Wireless (Ascension Island)|
|Intended use||Entities connected with Saint Helena, Ascension and Tristan da Cunha|
|Actual use||Various uses, sometimes connected to education and academia; a few sites actually on Ascension Island|
|Registration restrictions||2nd-level registrant must have professional or academic qualification ; 3rd level registrant must be resident on Ascension Island|
|Structure||Registrations are taken directly at the second level or at third level beneath various 2nd-level labels|
|Documents||Terms & Conditions; Rules|
|Dispute policies||Dispute Resolution Policy|
.ac is the Internet country code top-level domain (ccTLD) for Saint Helena, Ascension and Tristan da Cunha. It is administered by NIC.AC, a subsidiary of the Internet Computer Bureau based in the United Kingdom.
Use as an abbreviation for "academic"
- The University of Kurdistan - Hawler (http://ukh.ac/)
- Ralston College in Savannah, Georgia, USA (http://www.ralston.ac)
- The Faith Mission Bible College in Edinburgh, Scotland (http://www.fmbc.ac)
- The Mahidol Oxford Tropical Medicine Research Unit (MORU) in Bangkok, Thailand (http://www.tropmedres.ac/)
- INFORM (Information Network Focus on Religious Movements), based at the London School of Economics (http://inform.ac/)
- Newcastle University (http://www.unc.ac/), an online institution unconnected with Newcastle University in the United Kingdom and the University of Newcastle, Australia
- Many Indian institutes of higher education use .ac domain like Mumbai University: , IIT Delhi: , IIM Calcutta:  etc.
Several leading British universities have registered their .ac domain and use this to redirect to their .ac.uk webpages. Examples include:
- University of Oxford: www.oxford.ac directs to www.ox.ac.uk
- University of Manchester: www.manchester.ac directs to www.manchester.ac.uk
- University of Leeds: www.leeds.ac directs to www.leeds.ac.uk
- "IDN Code Points Policy for the .AC Top Level Domain" (PDF). nic.ac. 2013-05-20. Retrieved 2013-05-23.
- "The Pirate Bay Moves to .AC After Domain Name Seizure".