Block Diagram:

A block diagram is used to display the relationship among component groups, or stages in a circuit.  Within block form, it displays the path by a circuit from input to output that was shown in the Figure.  The blocks are drawn in the form of squares or rectangles linked through single lines along with arrowheads at the terminal end, displaying the direction of the signal path from input to output.  Generally, the necessary information to describe the stages of components is contained in the blocks.

Figure: Block Diagram