.ad is the Internet country code top-level domain (ccTLD) for Andorra. It is administered by Servei de Telecomunicacions d'Andorra, today called Andorra Telecom.

AD commonly refers to Anno Domini, Latin for "In the Year of (Our) Lord", applied to years following 1 BC in the Julian and Gregorian calendars.

In set theory, AD+ is an extension, proposed by W. Hugh Woodin, to the axiom of determinacy. The axiom, which is to be understood in the context of ZF plus DC_R (the axiom of dependent choice for real numbers), states two things:

1. Every set of reals is ∞-Borel.
2. For any ordinal λ less than Θ, any subset A of ω^{ω, and any continuous function π:λ}ω→ω^ω, the preimage π^-1[A] is determined. (Here λ^ω is to be given the product topology, starting with the discrete topology on λ.)

American Dad! is an American animated sitcom created by writers and executive producers Seth MacFarlane, Mike Barker and Matt Weitzman for the Fox Broadcasting Company. The series centers on the Smiths, a dysfunctional family consisting of parents Stan and Francine; their children Hayley and Steve; and their anthropomorphic pets Klaus and Roger. The show is set in the fictionalized version of the state Virginia. Unlike sister show Family Guy it doesn't exhibit its humor in the form of cutaway gags.

(abbreviated as AD or A.D.) and Before Christ (abbreviated as BC or B.C.) are designations used to label or number years used with the  Julian and Gregorian calendars. This  calendar era is based on the traditionally reckoned year of the conception or birth of Jesus of Nazareth, with AD counting years after the start of this epoch, and BC denoting years before the start of the epoch. There is no year zero in this scheme, so the year AD 1 immediately follows the year 1 BC. This dating system was devised in 525, but was not widely used until after 800.