Iconic communication uses icons or symbols to represent words or linguistic concepts. The reference of words is arbitrary, so, learning their meaning becomes necessary. Icons are easier to remember because it is often part of a consistent system of representation which provides a context. It is a well-known aid to memory to associate the thing to be remembered with a simple object to which it has a defined relationship; e.g., the following road sign suggests a narrow path ahead.
Graphics are images or visual representation of objects. Email or telephone does not use icons. Scripting is very rarely iconic (hieroglyphs, etc.)