An art director usually works alongside a copywriter to form a 'creative team'. Traditionally, the copywriter produces the words to go with the visuals created by the art director. These roles are becoming more blurred now though and it is likely that both will have an input on the visual and verbal content to produce the right look and feel for the advertising campaign.
The advertising art director works on the campaign from the beginning and receives details about the client, product, target audience and required advertising message, which helps to shape the advertising campaign.
Advertising art directors vary according to the agency they work for and the client brief.