An advertisement is made up of two parts: art & copy.
visual:art::text:copy
But the line is not always so distinct. Oftentimes an ad will rely solely upon a visual to relay a message. When this happens the visual must be strong, and able to stand by itself.
Examples here.
On the flip side lies copy. When an image is not standing alone, most often it is coupled with copy. Copy is arguably the most important part of the ad, however often is overlooked. To remedy this, work is put in to copy to make it as eye catching as the visual.
Copywriters & Graphic Designers work together to craft a visually appealing text.
This task of aesthetic —an area of particular interest to me — is Design. Design does heavy lifting for brand identity, message, tone, and all other things taken for granted on an item.
Design is a hard thing to explain. Students who wish to go to graduate school for design will, for two-four years, be tasked with trying to figure out what design is, what qualifies as design, and how far can design be taken.
As an introduction to design I offer these website links. They cover a broad spectrum of design & will showcase many facets of what it means to be designed.
The best way to understand design is take in as much as possible, and I encourage everyone to do so.