Charles Saunders Pierce was an american philosopher.Defined semiotics as the science of sign, he states that signs take the form of words, objects, sounds etc. The sign wouldn’t have a meaning until we have something to associate it with, or until we have learned what that means. Similar to Ferdinand Sausssare, they both look deeper into how meaning is formed.
He breaks Semiotics into three categories. Symbols, icons & index.
Symbols which rely on previous learnt behaviour , habits/rules. National flags & big company logos are examples of symbols. Big historical events will have certain symbols that collectively everyone will know.
Icons are any sign that resembles what it represents.This is used within pictograms, much like that female & male toilet symbols. We have these in all day to day life, we have become so use to seeing this format, in regards to instructional signs.
Index would have general link between the sign and the object. We only understand the instruction in relation to its placement. Much like street signs, there placement is crucial to how we react to them, different shapes having different meanings/