Poster design tips : A poster can be defined as a placard or bill, usually large and often incorporating photographs or illustrations, posted up for advertising or publicity or for decorative purposes. The functions of those which advertise include communication, selling and persuading. This does not preclude them being decorative. Indeed the first job of a poster is to attract the attention of the passerby and only once this is done can a message be delivered. A good poster then is one which is attention-grabbing, succinct, convincing and memorable.