Flowcharts use special shapes to represent different types of actions or steps in a process. Lines and arrows show the sequence of the steps, and the relationships among them. These are known as flowchart symbols.
The type of diagram dictates the flowchart symbols that are used. For example, a data flow diagram may contain an Input/Output Symbol (also known as an I/O Symbol), but you wouldn't expect to see it in most process flow diagrams.
Over the years, as technology has evolved, so has flowcharting. Some flowchart symbols that were used in the past to represent computer punchcards, or punched tape, have been relegated to the dustbin of history.