Final answer:
Direct mail advertising is the form of advertising involving the sending of postcards or flyers to prospective clients, targeted at specific demographic groups.
Step-by-step explanation:
The form of advertising that involves sending postcards or flyers to prospective clients is known as direct mail advertising. This type of advertising allows businesses or campaigns to target specific demographics with tailored messages.
For example, if a political campaign is trying to reach an older demographic in a certain area, they may use direct mail in conjunction with other forms of media such as television or print to effectively communicate their message.
However, with the shift in technology, traditional forms like direct mail are becoming less dominant as digital advertising strategies, especially on social media and the internet, become more prevalent.