The concept of Semiotics is about the usage of signs and understanding how they impact on us. They are all around us, from road signs to stop signs, to traffic lights.
They are a form of visual linguistics that have immense sway in our daily lives.
For a quick exercise. .here is the Grey alien. It is an iconic image, and well known type of 'alien'. The signifying word here is Alien. The image/illustration itself is the signified or icon.
What do you see in this sketch? Do you see just a mask, or more specifically an infamous character from a well known comic book? How has this particular icon, inspired a well known internet/hacker group?
A common site in shopping malls, and other convinence stores.
A destructive force of nature, that destroys all in its path. What is it?