this is not a pipe.

This is a famous painting by Rene Magritte called "The Treachery of Images." Magritte's caption says, (in French) "This is not a pipe."

Interesting eh?

this illustrates Magritte's point, which is simply that an image or sign of a thing is not the thing itself. One could make the same point with any number of images, signs, and symbols. Magritte's point is a simple one, so simple that we usually don't think about it. But precisely because we don't think about it, because we forget that the signs and symbols all around us are just that, signs and symbols, and not things themselves, we can come to take for granted, take as "natural," aspects of life that are anything but. we have to become aware that the names and labels are just names and labels. They represent the signified but they are not the signified. when you see a tree, you say that is a "tree". "Tree" is the signifier to signify the plant that has branches with big trunk to support it, so that plant is a signified.

Some labels and its meaning changes due time. These days semiotics serves as a very useful set of tools for identifying many of the formal patterns that work to make meaning in many aspects of our culture, particularly the media. Media constantly bombarded us with media messages with many symbols and signs that in order to identify and make meaning from them, we have to know at least how semiotics works. A particular advertisement would have its own ways of presenting its product, so we cannot simply just "see" an advertisement, we have to "read" the advertisement: the graphic, the lay out, the colours, the supporting elements, etc.

Try to read every advertisement that comes your way, it will give you more fun whenever you flip through the glossy mags as you can interpret meanings from them rather than just looking at them.