Buy this, buy that!

We all see infomercials, commercials, ads, billboards, pop-ups on our computers, no matter where we are, we see something telling us that we need it. Marketing is a complex mix of psychology, politics, current trends, time of year, and the demographic you wish to reach.
Example: when advertising things such as nerf guns, you picture children playing with them, but as of late, that former population of children are now teens, so in all the ads, all the models are teen boys. Its a subtle way to identify with a demographic that's grown up, and it also draws in little kids who see that and think "big kids like that, therefore it must be cool!" But if you want to sell a product similar to nerf guns, you have to use teens who look as though they've really been fighting, thus making it realistic and pulling in the people who want to have that "awesome" feeling of actually fighting.

When selling makeup or other such products (shampoo, deodorant, and other hygiene items) you use an attractive actor, if it's a man, typically tall, well cut, dark haired, and with a brown haired, beautiful woman who is about as tall as his neck. This is a subliminal message to our subconscious that by using this product a beautiful person will find you immediately attractive. With women's products, it's typically a blond woman, and a dark haired man (again), who is taller than the woman, but only up to his chin. He also appears to be utterly transfixed by the woman using the product. Another subliminal message that this product will make you totally individualized and noticeable to other people, thus tricking the people who fall for these marketing gimmicks to buy the product.

Vacations. Who doesn't love them? Don't the ads they show make you just wanna pack up your bags and go?
Good. That means it worked. Vacations are different from makeup. They don't want you to think you're extraordinary for using the product. They want you to think ordinary people go on extraordinay trips, so they use people, who are maybe semi attractive (real people) to say "hey, this can be you!" and coupled with cheap rates, they're right. You go the vacation, and they make more ads.

What they don't tell you, is that the real point of marketing is to tell you you're stupid, and still trick you into buying their product. They do this by advertising something unnecessary that they tell you that you need or you'll be stuck dealing with horribly undesirable bruised banana's (NOOOOOO!)
See the banana case, which you obviously need.