Semiotics are the theories that explores how systems of sign works to make a meaning. Also how we represent ideas and create meanings using a range of tools like words and images.
This idea of semiotics helps us understand how visual communication works. It brings an understanding how words and images work together to make sense in our minds. For example, if we think of the word dog, we would vision a dog or we'll know what a dog is because that semiotic exists.
This is an example of road signs that is understood universal by car drivers. These sets of signs has a set of instruction or meanings to it that is required to be understood on the roads. In graphic design, a good designer would understand how we associate signs with meaning so we can use this theory and put it into practice.
