A, B, C1, C2, D, E: UK socio-economic classifications that define the status of individuals by their wealth and profession from the top level As, downwards.

Above-the-Line Advertising: advertising which employs one of six main media - the press, television, radio, cinema, posters and online.

Acquisition Cost: the cost to an advertiser to gain a new customer

Advertising Platform: the basic issues or selling points that a company wishes to have included in an advertising campaign

Advertising Planning Process: the steps or stages taken in planning an advertising campaign; the steps include identifying the target market, establishing the advertising objectives, developing the advertising budget, developing the advertising strategies, selecting the appropriate media, and evaluating the advertising effectiveness

Advertising Research: research done to test the effectiveness of advertising; this may include the pre-testing and post-evaluating of specific advertisements and campaigns

Ad server: a computer, normally operated by a third party, that delivers and tracks online advertisements independent of the web site where the ad is being displayed.

Ad serving: the delivery of online advertisements through an independent software operator enabling the detailed tracking of a campaign performance

Advertorial: paid-for advertising produced in the style of the editorial of the magazine or newspaper in which it appears, but clearly labelled as advertising or promotion

Average Issue Readership (AIR): estimated number of people on average to have seen or read an issue of a publication

Alternative Advertising: advertising which uses media other than the traditional media; examples of alternative advertising include advertising signs on parking meters and supermarket shopping trolleys, in-store video screens, etc

Audience: a group of people who see or hear an advertisement or advertising campaign

Audited Circulation: circulation that has been audited, generally by an independent company

Average Frequency: estimate average number of opportunities to see advertising insertions in a given media schedule. (See OTS)

Average Net Paid: average paid circulation per issue arrived at by dividing total circulation of all issues during an audit period by the number of issues for the same audit period.