".ac" is the internet ccTLD (country code Top Level Domain) for Ascension Island.
Registration for this domain is open to anyone.
For more information see: http://en.wikipedia.org/wiki/.ac
Most countries have their own Internet TLD. Each country controls the policies governing their own TLD.
For example, ".ca" is the TLD for Canada, and CIRA (The Canadian Internet Registration Authority) restricts their registration to Canadian residents.
Other Internet TLDs aren't associated with any particular country, such as ".com", ".net", ".org", and some others.
There are a total of about 280 Top Level Domains.
For a fairly comprehensive list of TLDs see:
http://en.wikipedia.org/wiki/List_of_Internet_top-level_domains
http://filext.com/file-extension/AC
If you mean .ac.uk as shown in a web address, the ac means "academia" - i.e. part of the education system. The web address could belong to a school or university, for example.
In web addresses, 'ac' is usually reserved for academic institutions such as schools and univerities. 'in' is the suffix for India, so an address ending in 'ac.in' would usually be a university or such based in India.
Trast AC ended in 1938.
AC Ballerup ended in 2002.
www.myspace.com/acdc. You Could Also Attempt To Write The Band Via Columbia Records. Failing That, Type AC/DC Fan Mail Address Into Your Google Toolbar. You Will Be Directed To Click On A Web Page That Should Give You An Address To AC/DC'S Australian Record Label, Albert's, Which Will Direct All Fan Letters To The Band.
Cardiac and hypochondriac end in -ac
AC St. Louis ended in 2011.
Excelsior AC Roubaix ended in 1995.
Plug in port for ac.
Cowbois ac Injans ended in 2007-03.
AC in AC milan stands for Assosiation Calcio Milan AC in AC milan stands for Assosiation Calcio Milan
AC stands for "As Custodian for"