Semiotics, where we derive meaning from symbols and the relationships we have within our culture, religion, feeling of nationalism, etc. Semiotics worm their way into our minds and can be used to influence us to go one way or another. So, what could this have to do with marketing?
EVERYTHING
In marketing, the whole point is to sell to the masses. There is only one way in which this possible, and that is to understand who your target is.
Example (women):
Just throwing this one out here. Nail polish, there are many different types and some appear to be better than others, but what does this one particular ad "say" to a consumer? Exclude the nail polish (signifier) and look at everything that is pointing to it. There is, quite obviously, a set of script letters that state "Nail Polish Love" which draw your eyes in not one, but three directions. On either side of this script are "shiny objects" one of which just so happens to be an engagement ring. The bright piece of this, interestingly enough, is the woman's slightly curved lips that are just close enough to a smirk. Now, people may disagree with my assessment on this, but any and every time I see slightly curved lips, I see the "I am better than you" smirk with just a hint of a challenge or secrecy. This whole ad points to the idea that this nail polish either makes this woman better than you because she is loved or has love due to this polish OR that you will get love if you love on this polish.
Just an example of how marketing ploys sort of target the baser human needs to be loved and to accept a challenge from some unknown "superior".
Marketing thrives on the use of semiotics. Morgan Spurlock exemplifies how this happens on TedTalks.
Enjoy if you choose, it is about a twenty minute video, and he goes through how and why some advertising works versus why others do not.
I leave with this thought: Advertising+no semiotics= No ads, no sell point, no nada.